Faulty Repair of Fuel-Control Unit Cited in Engine Flameout

FLIGHT SAFETY FOUNDATION Aviation Mechanics Bulletin MARCH–APRIL 2003 Faulty Repair of Fuel-control Unit Cited in Engine Flameout

SINCE 1947 FLIGHT SAFETY FOUNDATION Aviation Mechanics Bulletin Dedicated to the aviation mechanic whose knowledge, craftsmanship and integrity form the core of air safety. Robert A. Feeler, editorial coordinator March–April 2003 Vol. 51 No. 2

Faulty Repair of Fuel-control Unit Cited in Engine Flameout ...... 1 Maintenance Alerts...... 11 News & Tips ...... 17

On the cover: Accident investigators compared a new unadjusted fuel-control-unit flyweights’ clip with one that was properly adjusted. The accident report said that the flyweights’ clip probably had never been adjusted in a Hughes 369D that was substantially damaged during a landing in a wooded area after an engine flameout. (Photo: New Zealand Transport Accident Investigation Commission)

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A report by the New Zealand Transport Accident Investigation Commission said that symptoms of engine overspeeding in the Hughes 369D helicopter were improperly diagnosed for more than 2 1/2 years before the accident.

FSF Editorial Staff

At 0705 local time March 23, 2001, The New Zealand Transport Accident the pilot of a Hughes 369D helicop- Investigation Commission (TAIC) said, ter being flown on a deer-hunting in the final report on the accident, that flight in southwestern New Zealand the engine “flamed out in flight during experienced an engine flameout as normal application of power because he applied collective control to stop of a defective fuel-control unit [FCU] the helicopter’s descent. He landed that induced engine hunting [oscillat- the helicopter in trees on a moun- ing: alternately running too fast or too tainside at 3,000 feet, about 12 kilo- slow] while at reduced power.” meters [7.5 statute miles] northwest of Milford Sound. The helicopter Other findings included the following: received substantial damage; neither the pilot nor the helicopter’s owner, • “Repeated engine overspeed- who was working as a crewmember, ing symptoms resulted after was injured. [reinstallation] of the repaired fuel-control unit, over a period of and a class 1 medical certificate. He two years and eight months be- had accumulated 3,000 flight hours, fore the accident, but these were including about 850 flight hours in misdiagnosed as being power tur- Hughes 369 helicopters. bine governor [PTG]–related; The accident helicopter, which usu- • “Comprehensive troubleshoot- ally was flown for air tours and other ing should have been carried out commercial transport operations, was after the power turbine governor manufactured in the United States in had been changed several times, 1977. When the accident occurred, the which could have isolated the airframe had accumulated 7,278.55 engine overspeeding problem to hours of operation, and the Rolls- the fuel-control unit and averted Royce Allison 250-C20B engine the accident; had accumulated 8,073.31 hours of • “The performance of the deficient operation. The last inspection was fuel-control unit may have dete- performed Feb. 22, 2001, at 7,212.2 riorated further over time, until airframe hours; during that inspection, it ultimately brought about the a new compressor was installed in the flameout; engine. • “Improper monitoring and control The morning of the accident, the pi- of commercial engine bulletins lot conducted a takeoff from Milford resulted in the fuel-control unit Sound Aerodrome at 0645. The heli- not being modified to the latest copter, which was operated by Mil- specification. This did not con- ford Helicopters, had fuel for about tribute to the flameout; [and,] two hours of flight. The pilot said that • “This investigation indicated samples of fuel taken before the flight [that] a quality assurance from the helicopter’s belly drain and problem had existed within the the airframe fuel filter revealed no Australian component overhaul contamination. facility at some time. Because of the potential for safety-critical Weather for the flight was clear, with components to affect the safety good visibility and calm winds. of flight, a more in-depth investigation into the overhaul facility’s The report said that, about 10 minutes performance is required.” after departure, the pilot observed “an unusual response from the helicopter, The pilot of the accident helicopter as though it had flown through its own was 29 years old and held a com- turbulence.” Simultaneously, the amber mercial pilot license (helicopter) engine re-ignition light illuminated.

2 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 3 The pilot observed no other cockpit assistance, and the crew of another indications of abnormalities. helicopter rescued them.

“About five minutes later, when Examination of the wreckage revealed the helicopter was approaching a that the engine was not rotating when 3,500-foot knoll to drop off a deer the accident occurred. The fuel was carcass attached to a sling, the pilot not contaminated, and there were felt the helicopter ‘twitching,’ and no deficiencies in the helicopter fuel said later that the helicopter ‘didn’t system. feel right,’” the report said. “There were no cockpit indications of any The report said that, during tests abnormalities. on the ground, the engine “started normally … and ran satisfactorily at “About a minute after leaving the idle with about 10 psi engine torque. knoll, the crew saw two deer run- As engine power was increased to ning down the side of a hill. The around 15 psi torque, the engine pilot said he lowered the collective began hunting. At 30 psi, the hunt- lever and reduced engine power to ing became pronounced, with the about 15 pounds per square inch torque rapidly fluctuating some (psi) of torque and descended after 15 psi either side. The fuel flow the deer. The helicopter descended fluctuated rapidly between about some 500 feet before the pilot ap- 78 pounds [35 kilograms] per hour plied collective normally to arrest and 160 pounds [73 kilograms] per the descent. The engine did not re- hour. Minimum normal engine fuel spond to the demand for increased flow at idle is around 79 pounds [36 power. Instead, there were multiple kilograms] per hour. audio [cockpit warnings] and visual cockpit warnings that the helicopter “Engine torque was increased slowly, engine had lost power. The pilot also and the hunting subsided as power noticed the engine gas producer tur- was increased above about 50 per-

bine speed (N1) decaying.” cent. At maximum power, the engine parameters were within specifications. The pilot moved the collective lever to As power was reduced below about determine whether the engine would 50 percent, the hunting recommenced, respond. There was no response, so with the same results.” he conducted an autorotation in a wooded area on a mountain slope. The report said that because of the The helicopter rolled onto its left side, oscillations in engine speed, rapid and the two occupants exited without acceleration and deceleration tests injury. They used a radio to request were not performed.

2 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 3 Adjustments were not made during had two cracks in the governor (drive the tests of the FCU, the main compo- body) housing. The cracks allowed nent of the engine fuel-control system. the housing to twist, which affected Later, the PTG was replaced with a the normal operation of the FCU. The different unit; in subsequent ground repair job card recorded the on-receipt runs, the oscillations continued. Then, condition of the unit, stating that there the FCU was replaced with an over- was ‘different L/W (lock wire) on bel- hauled FCU, and the engine started lows screws. Cut L/W (lock wire).’ The normally and accelerated normally governor housing was replaced, along throughout its power range and there with a seal and nut. The defect inves- were no oscillations in engine speed. tigation report stated [that] the gover- Rapid acceleration and deceleration nor housing had been crack-checked tests revealed that the engine was op- at overhaul and that no cracks were erating within specifications with no detected. The repair records stated overspeeding. At the maximum power [that] the flow body assembly was setting, the engine delivered 6 percent not dismantled. … The operator be- more than rated power. lieved the cracking occurred during service because the starter-generator The FCU in the accident helicopter developed vibrations.” was a Honeywell Bendix FCU (part no. 2524644-29) that last had been The repair was completed June 24, overhauled in December 1996 by 1998, and the FCU was tested and an Australian component-overhaul reinstalled in the accident helicopter facility, Lucas Aerospace (now TRW July 31, 1998. Aeronautical Systems). The FCU was installed — with zero hours since The report said that on March 15, 1999, overhaul — in the accident helicopter Rolls-Royce Allison issued alert com- by a maintenance technician in New mercial engine bulletin (CEB) A-1361, Zealand in March 1997. revision 1, calling for replacement of the FCU’s internal springs. (The CEB was first issued Oct. 5, 1998.) The Overspeeding spring-replacement was to be per- Reported in 1997 formed within 150 hours of receipt of the CEB, or no later than Oct. 31, In December 1997, at 237 hours since 1999. The spring-replacement had overhaul, the FCU was removed “be- not been performed on the accident cause it ran constantly at 110 percent helicopter, and the internal springs had power turbine speed (N2),” the report not failed. The report said that failure said. “The FCU was returned to TRW of the springs would have resulted in for repair. Records showed the FCU immediate engine deceleration.1

4 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 5 “The operator did not receive service Maintenance personnel checked bulletins and said he was not aware the PTG rigging in April 1999, of CEB A-1361,” the report said. before Flightline became the “Flightline [Flightline Aviation, the helicopter’s approved maintenance approved maintenance organiza- organization. tion] received service bulletins but did not pass them on to the operator. On Aug. 6, 1999, Flightline mainte- Flightline’s chief engineer [maintenance personnel removed the PTG (at nance technician] said he normally 1,316 hours time in service since its reviewed all applicable service bul- last overhaul) for overhaul. Another letins, but would not necessarily PTG was installed as a temporary re- discuss them all with the various placement, and the operator said that, operators, because administratively “although there seemed to be some it was very difficult to achieve. In improvement with the [replacement] this instance, he was not aware of PTG, the engine speed control was CEB A-1361 and therefore had still not right.” not discussed it with the operator. CEBs were received by Flightline’s The overhauled PTG was reinstalled engine shop manager and filed. The on April 5, 2000. On June 26, 2000, shop manager said he took no action Flightline requested that a different because the requirements would be maintenance organization remove fulfilled at the next overhaul.” the PTG (at 67 hours time in service since the overhaul) because of engine The report said that the engine in the overspeeding and reinstall the tempo- accident helicopter was equipped with rary replacement PTG. a Honeywell Bendix PTG (part no. 2524769-14), which was examined “The PTG was returned to TRW for several times during the two years examination and testing,” the report before the accident because of the said. “Flightline requested the inves- operator’s concern that the engine tigation report, which stated [that] was “overspeeding when power was the unit was governing slightly early reduced and [was] not holding its revs (0.8 percent) at normal governing [revolutions per minute].” range but was governing slightly late at overspeed conditions.” The operator said that the problem was most noticeable in turbulence The PTG was recalibrated to over- and that, “if the collective lever haul limits and on Oct. 24, 2000, was lowered fully, the engine would was reinstalled in the engine by the overspeed, and the collective had to maintenance organization that had be raised to prevent it.” removed it.

4 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 5 On Jan. 16, 2001, Flightline again during the first few hours of operation asked the other maintenance organi- after an overhaul and that fluctuations in zation to remove the PTG because of engine speed could occur as a result. engine overspeeding and to reinstall the temporary replacement PTG, which had been operated for 146 hours Operator Wanted since its last examination. The accident Additional Maintenance helicopter’s PTG was again returned to TRW for examination and tests. The operator said that the engine speed-control problem continued Flightline reinstalled the PTG in the ac- and that he had decided — although cident helicopter on Feb. 22, 2001, dur- he had not told maintenance person- ing the 300-hour maintenance check. nel — that he again would have the PTG removed. “After the maintenance, the helicopter was run several times to track the ro- The report said that the maintenance tor blades,” the report said. “During manual and the manufacturer’s opera- the first ground run, [maintenance] tion and service manual for the FCU engineers noticed the engine hunting and PTG said that a probable cause (about 3 percent). This seemed to the of overspeed incidents could be a de- engineers as though the pilot was fective FCU or a defective PTG. The adjusting the engine speed manually. manuals said that if the idle speed On a second ground run, the engine was normal during a ground run con- hunted about twice, and once on a ducted under specific conditions, the third [ground] run. The hunting did PTG was probably the cause of the not occur on subsequent [ground] problem; if the idle speed was high, runs. A test flight was carried out, the FCU was the likely cause. and the pilot and engineers were satisfied with the helicopter’s perfor- “Flightline advised [that] because mance. … A few days later, the chief the engine problems had not specifi- [maintenance] engineer asked the cally been reported as overspeeding operator about the helicopter, and incidents, the part [FCU] was not fol- the operator indicated he was satis- lowed,” the report said. “The [report- fied with it. The operator, however, ed] concern was more about unstable had not subjected the helicopter to or erratic engine operation.” demanding operations, such as deer hunting, at that point.” The operator and the pilot said that until the morning of the accident, they Flightline maintenance personnel said had not observed the problems that that PTGs sometimes were “sticky” preceded the accident.

6 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 7 Further tests revealed that the PTG the 1998 repair and not adjusted. The and the fuel pump had not contributed clip weight stops resembled those of an to the engine flameout. “unadjusted new item,” the report said. Maintenance records did not show that Further tests of the FCU, however, the flyweights’ clip had been replaced, revealed that the flyweights’ clip was and entries in the records for the FCU adjusted improperly, and as a result, the overhaul and FCU repair both showed flyweights’ movement was restricted to that the clip weight stop adjustments less than half of the required distance. were appropriate.

The FCU is designed so that its two “This suggests either [that] the data flyweights rotate at a speed propor- [were] entered on the repair documents

tional to engine N1. As N1 increases, without the appropriate measurement centrifugal force pushes the flyweights’ check being completed, or the check

path outward. The report said that if N1 was inadequate,” the report said. increased beyond normal values, “the flyweights’ travel would cause the The engine oscillating probably oc- FCU’s governor lever to bleed off gov- curred soon after the repaired FCU

ernor bellows air pressure (PY) and bring was installed in the engine, but “the about a fuel-flow reduction to prevent right mix of parameters to cause a

the engine overspeeding. N2 was nor- flameout may not have come together mally held constant by the PTG, but as until the day of the accident,” the re- collective pitch was changed, the load port said. “What is likely is [that] the on the power turbine changed, tending FCU’s performance progressively

to change N2. Fuel flow was increased worsened with normal use and wear or decreased to affect the gas flow veloc- until the situation became critical on ity, and the gas producer turbine may the day of the accident. In addition, change its speed accordingly to supply the [installation] of a new engine the power required to help maintain a compressor 66 [flight] hours before

constant N2.” the accident would have increased compressor discharge efficiency and “Because the FCU flyweights’ clip re- engine performance. This could have stricted the flyweights’ travel to less further degraded the ability of the de- than half the required distance, the fective FCU to function adequately.” FCU could not adequately control any

tendency for engine N1 overspeeding,” The FCU tests also revealed that the

the report said. acceleration bellows pressure (PX) air bleed restrictor orifice was enlarged at The report also said that the flyweights’ one end and that the surface around that clip probably had been replaced during end was scratched. At the opposite end

6 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 7 of the restrictor, a screwdriver slot was TRW had been approved by the Aus- deformed. The manufacturer said that tralian Civil Aviation Safety Author- the condition of the orifice probably ity (CASA) to perform overhauls and caused no serious anomalies with the repairs of various aircraft components, functioning of the FCU. Nevertheless, including Honeywell Bendix FCUs the manufacturer said that the air bleed and PTGs on Rolls-Royce Allison “was in an unserviceable state because 250-C20B engines. Honeywell Bendix of its physical condition.” also authorized TRW to perform the work. The New Zealand Civil Aviation TRW said that the orifice should have Authority accepted CASA approval been inspected during overhaul and of TRW for repairs and overhauls of that the PX air bleed would have been components on aircraft registered in removed and discarded if it had been New Zealand. in poor condition. Overhaul records did not show that the PX bleed had been re- TRW records showed that the FCU placed. The report said, “Someone out- overhaul was performed by one main- side of TRW could have tampered with tenance technician, and the work was the PX bleed and replaced the lock wire, inspected and approved by “a fitter, which would explain the repair docu- who [had authority] to sign off the mentation stating [that] the lock wire work,” the report said. Another main- near the access to the PX bleed had been tenance technician performed bench disturbed. … There was no reason why tests and made required adjustments. the PX bleed should have been removed after overhaul, and there was no record When the FCU was returned for repairs, indicating it had been. Alternatively, the the same fitter performed and approved TRW technician who overhauled the his own work. Another maintenance unit may have overlooked inspecting technician performed bench tests. or replacing the PX bleed, but this could not be established.” “Allowing a single authorized and qualified person to complete and sign During the subsequent repair, the off their own work was an approved FCU flow body assembly was not practice, and one that was followed dismantled, and such action was not by other overhaul companies,” the re- required. Nevertheless, the report port said. “After a rebuild or repair, said, “it is reasonable to expect an the units were subject to separate overhaul facility, having observed test-bench checking.” inconsistent security lock wiring and being concerned about potential inter- The report said that in a June 1999 in- nal tampering, to have carried out an ternal audit, TRW checked the work examination of this area internally.” folders for six recently completed jobs

8 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 9 and found “a total of 35 major [issues], “Flightline Aviation does, howev- 31 minor [issues] and four question is- er, as a reputable and professional sues.” The report did not say whether organization, obtain, view and records about the accident helicopter’s generally advise customers of FCU were included in the audit. the existence of manufacturer’s service bulletins. Service bulle- After the accident, Flightline sent the tins are received and assessed for FCU and the PTG from another Rolls- applicability so that the customer Royce Allison 250-C20B engine for has the option of accepting or re- examination by another independent jecting their intent”; and, Australian component overhaul facil- • The managing director should ity. The PTG had been overhauled by review the organization’s engine the TRW fitter who had completed troubleshooting procedures to the repairs on the accident helicopter’s “ensure comprehensive fault FCU. The report said that examination diagnosis is carried out when a of the PTG, which had accumulated repeated component change does 780 hours since the overhaul, revealed not rectify a known problem.” a number of deficiencies that rendered the PTG unserviceable. The report said In response, the managing direc- that in addition, the authorized release tor said, “All relevant trouble- certificate for the overhauled PTG shooting procedures (and more) — signed by the fitter — said that CEB were carried out in accordance 1327, incorporating new drive bearings, with the maintenance manual had been incorporated; nevertheless, pertaining to the defect informa- older bearings were in the unit. tion supplied at the time. “Flightline Aviation’s engineering As a result of the investigation, TAIC staff [is] well-qualified and well- issued the following two recommen- experienced concerning this engine dations to the managing director of type. All documented troubleshoot- Flightline Aviation: ing procedures were followed in • The managing director should accordance with the maintenance establish a system for “proper manual, and it is only in hindsight monitoring and control of service — with a complete set of facts — bulletins.” that anyone could conclude that repeated component changes in this In response, the managing di- instance might not have been the rector said, “There is no formal best course of action. … requirement to establish a system to ensure proper monitoring and “The intent of the safety recom- control of service bulletins. … mendation refers specifically to

8 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 9 this one engine type. ‘Trouble- issuance of “one documentation- shooting procedures and com- related NCN,” and in April 1999, one prehensive fault diagnosis for noncompliance notice was issued “cit- repeated component changes’ ing no corrective action following an relates not only to this one task internal audit.” The ATSB report did but all troubleshooting tasks. It is not discuss other details of the non- a generic requirement, and Flight- compliance notices. line cannot implement additional processes concerning one task The ATSB report also said that the over any other. As such, we believe U.S. Federal Aviation Administration there is no necessity to implement (FAA), which monitored the facility this safety recommendation in ad- because of its work on components dition to our current practices.” that were used in U.S.-registered aircraft, had revoked in 1997 the fa- The managing director also said, cility’s FAA air agency certificate “be- “Flightline Aviation supports and cause the facility did not conform to promotes a rigorous safety culture and FAA regulations.” FAA reinstated the associated work practices. The intention certificate in December 2000. here is not to wholeheartedly disagree with TAIC safety recommendations but, CASA’s records did not include more importantly, to ensure that any rec- documentation of the FAA actions, ommendations are based upon factually and CASA said that “there was no for- supported data and that requirements mal mechanism through which CASA are necessary, able to be effectively would be advised of the results of any implemented and measurable.” surveillance action taken by a foreign airworthiness agency on an Australian Also as a result of the TAIC inves- certificate-of-approval holder.” tigation, the Australian Transport Safety Bureau (ATSB) conducted an As a result of its investigation, ATSB investigation of the TRW facility, not recommended that CASA “consider identified by name in the ATSB report. formalizing a method to obtain and The ATSB report said that CASA had review the results of any foreign audited the maintenance facility in airworthiness authority audit of Aus- February 1996 and had issued three tralian certificate-of-approval hold- noncompliance notices “outlining dis- crepancies.” A December 1997 audit ers.” [CASA said, in a Feb. 4, 2003, resulted in two noncompliance notices response to the recommendation that (NCNs), a June 1998 audit resulted its representatives would “consult in one documentation discrepancy, with the relevant foreign airworthi- a September 1998 audit resulted in ness authorities” to develop formal

10 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 11 procedures for obtaining results of required by an airworthiness foreign audits of Australian certifi- directive (AD). Neither the cate-of-approval holders.] U.S. Federal Aviation Admin- istration, the authority for the [FSF editorial note: This article, ex- engine’s country of origin, nor cept where specifically noted, is based the New Zealand Civil Aviation on New Zealand Transport Accident Authority had issued an AD to Investigation Commission Aviation require implementation of alert Occurrence Report 01-003 Hughes commercial engine bulletin A- 369D ZK-HMN, in-flight engine 1361. Normal aviation practice flameout, 12.5 kilometers northwest does not require that all ser- of Milford Sound (17 pages with vice bulletins be implemented photographs) and Australian Transport automatically. The operator’s Safety Bureau Air Safety Recommen- operations manual said that ADs dation R20020134 (three pages).] or service bulletins that affected the accident helicopter were to be Note reviewed by the operator and the approved maintenance organiza- 1. Implementation of service bul- tion to determine what action was letins is not mandatory unless required.

MAINTENANCE ALERTS

Error Leads to (NTSB), the U.S. Federal Aviation Installation of Defective Administration (FAA) found two pre-existing cracks and corrosion in Landing Gear Parts the area where the landing gear had The right main landing gear of a Grum- collapsed. man G-73, a twin-engine amphibious aircraft being operated as a scheduled “Review of paperwork by company passenger flight, collapsed while the maintenance personnel revealed aircraft was being taxied to the parking that components had been sent to ramp. There were no injuries to the two a laboratory for examination,” said pilots or the 17 passengers. the report. At the laboratory, the landing gear parts had undergone According to the report by the U.S. magnetic-particle inspection and National Transportation Safety Board X-ray inspection.

10 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 11 “Upon return of the components, the McDonnell Douglas DC-9-10, DC- paperwork indicated that two compo- 9-20, DC-9-30, DC-9-40 and DC-9-50 nents had been rejected due to cracks,” series airplanes, and the C-9 military said the report. “A red tag was also version of the DC-9. (The McDonnell attached to the [laboratory] report.” Douglas Corp. merged with The Boe- ing Co. in 1997 and is now Boeing, The landing gear containing the Douglas Products Division.) rejected parts nevertheless was pre- pared, painted and installed on the Within 18 months of the effective date accident airplane. Following the ac- (Jan. 17, 2003) of the AD, operators cident and investigation, the airline’s of the affected aircraft are required director of maintenance said, “At this to perform a one-time general visual time, I realized that I had tagged an inspection of circuit breakers to deter- unserviceable part [as] serviceable by mine the manufacturer of the circuit mistake,” the report said. breakers, in accordance with McDon- nell Douglas Alert Service Bulletin NTSB said that the probable cause of DC9-24A171, Revision 01, dated the accident was “the improper review Sept. 21, 1999, excluding Evaluation of component records by company Form. If any Wood Electric Corp. maintenance personnel of returned or Wood Electric Division of Potter landing-gear components from a Brumfield Corp. circuit breaker is laboratory for [magnetic-particle] found, that circuit breaker must be and X-ray [inspection].” replaced with a new circuit breaker in accordance with the service bulletin. Airworthiness No circuit breaker having a part num- Directive Calls for ber listed in paragraph 1.A.2 of the service bulletin may be installed on DC-9 Circuit-breaker any affected airplane, the AD said. Inspections About 830 DC-9s in the affected U.S. Federal Aviation Administration series are in service worldwide, FAA (FAA) Airworthiness Directive (AD) said. An estimated 580 airplanes of 2002-25-04 has been issued “to U.S. registry will be affected. prevent internal overheating and arc- ing of circuit breakers and airplane Earlier ADs required similar in- wiring due to long-term use and spection of other aircraft types. AD breakdown of internal components 2001-08-16, issued on April 17, of the circuit breakers, which could 2001, applies to certain McDonnell result in smoke and fire in the flight Douglas Model DC-8 series airplanes compartment and main cabin” of and requires a one-time inspection

12 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 13 to determine the manufacturer of the of the helicopter and put his hand on the circuit breakers, and corrective action, throttle and confirmed [that] it was fully if necessary. AD 2000-09-07, issued open,” said the accident report by the on May 3, 2000, applies to certain New Zealand Transport Accident Inves- McDonnell Douglas DC-10-10, tigation Commission. “He lowered the DC-10-15, DC-10-30, DC-10-30F collective lever and activated the rotor

and DC-10-40 series airplanes, and speed (NR) selector switch to ensure KC-10A (military) airplanes. [that] it was fully ‘beeped’ to maximum

NR.” [The “beeper” is a thumb-activated Deferred Maintenance switch by which the pilot makes small adjustments to N .] Item Unrecorded, R Overlooked The helicopter was landed heavily but it maintained some forward speed and A Bell JetRanger 206B II helicopter became airborne again, reaching an was being used to apply agricultural altitude of about 40 feet AGL. After chemicals northeast of Cromwell, rotating about 270 degrees, the heli- New Zealand, on Sept. 11, 2001. An copter descended to the ground and instructor pilot and a trainee pilot came to rest upright with the throttle were on board, and the trainee pilot fully open and the engine turning. The was the pilot flying. During the climb pilots shut down the engine by moving on the aircraft’s 10th flight of the the fuel selector to the off position. day, at 40 feet to 50 feet above ground The pilots were not injured. level (AGL) and about 50 knots indicated airspeed, the trainee pilot Maintenance records showed that lowered the collective lever and re- on March 17, 2001, the company duced power from about 100 percent that maintained the helicopter had torque to about 90 percent torque. The assigned an engineer to conduct field instructor pilot, who had been looking maintenance, and that the engineer

out the windshield, sensed the power had replaced the N2 tachometer reduction and turned his attention to generator because there had been no

the power-turbine-speed (N2) indica- N2 indication on the dual gauge that

tor, which showed the power-turbine indicated both NR and N2. speed steadily decreasing and approaching 80 percent. The engineer said that he had de-

termined that the N2 tachometer “Believing the engine was losing power, generator-drive-shaft receptacle was as though the throttle was being smooth- worn but serviceable. To replace the ly rotated to the closed position, [the in- receptacle, which formed part of a structor pilot] immediately took control gear in the accessory gearbox, the

12 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 13 engine would have to be removed the next scheduled maintenance on from the helicopter and the accessory March 27, 2001, and during later gearbox opened. Because the work was maintenance. too complex to be carried out in the field, the engineer planned to replace “Consequently, the RTV deteriorated the generator-drive-shaft receptacle at over time and failed to prevent further the next scheduled maintenance time, wear, or failed to continue to assist in and meanwhile inserted red RTV (a maintaining a positive drive, between sealant) into the receptacle to prevent the N2 tachometer generator-drive- further wear or slippage. shaft and its receptacle, until slippage between them occurred,” said the re- The report said, “The engineer recorded port. “On the accident flight, the drive the maintenance action on a company failed, causing the N2 gauge indication work record sheet for the helicopter, to decrease.” which formed part of the helicopter logbook records, but he did not record The report found that “the mainte- the need to subsequently replace the nance company and [the] operator did drive-shaft receptacle. The engineer not have a suitable system in place said he overlooked transferring the to make certain that any additional requirement to replace the receptacle to maintenance action required follow- the Additional Maintenance Due sec- ing field maintenance was recorded tion on the maintenance advice form, correctly and completed at the next and consequently he did not remember available aircraft servicing.” The to complete the action. quality manager for the maintenance company subsequently advised the “There was no loose-leaf [entry] or commission that corrective action had direct entry made in the helicopter been taken, and a system established logbook concerning the N2 tachometer- to ensure that required follow-up generator replacement. Neither the action would be recorded and per- pilot at the time, nor the engineer, formed at the appropriate time. made any entry in the aircraft technical [log] or daily flight log carried in Uncontained Engine the helicopter, and the operator was only verbally made aware of the need Failure Follows to replace the receptacle.” Ingestion of Bellmouth

No erroneous N2 gauge indications The flight crew of a McDonnell Doug- were reported subsequently, and the las DC-10-30F, engaged in cargo replacement of the N2 generator-drive- operations, began the takeoff from shaft receptacle was overlooked at Amsterdam (Netherlands) Schiphol

14 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 15 Airport on a scheduled flight to Lon- elevator, some damage was visible on don (England) Gatwick Airport. The the skin.” pilots advanced all throttle levers to

50 percent N1 (low-pressure fan Investigators could find no evidence speed) and engaged the autothrottle of damage to the accident engine prior system. The selected power setting to its failure.

for takeoff was 103.4 percent N1

derated. At about 75 percent N1, the “According to the [no. 2 engine] in- flight crew noted heavy vibration, strument read-outs registered during and the captain, who was the pilot previous takeoff and cruise, the engine flying, observed an indication that operated within [prescribed] limits,” the exhaust gas temperature (EGT) said the report. “The parameters for the tail-mounted no. 2 engine was showed average values, without any higher than the EGT for the other two deviations. Also, the [no. 2 engine] engines. The Schiphol tower air traf- trend-monitoring parameters pre- fic controller (ATC) reported that the sented normal values. The labora- no. 2 engine was on fire, although no tory examination of the fan blades warnings were given by the engine- did not reveal pre-existing cracks or fire-warning system in the cockpit. anomalies in the fan-blade materials. … Overall, it can be assumed that The takeoff was rejected, and because prior to the serious incident [the no. 2 of the high EGT indication and the engine] was in good condition.” ATC warning, the crew performed the “Engine Fire or Severe Dam- During the investigation, a borescope age” checklist. Nevertheless, when inspection of the no. 2 engine indi- the aircraft rescue and fire fighting cated that a substantial quantity of personnel arrived, there were no in- debris had been ingested. dications of a fire in the no. 2 engine, a General Electric CF6-50C2. None Investigators considered the possibility of the four crewmembers was injured that the engine had ingested ice dur- in the accident. ing the flight into Amsterdam, which had concluded about four hours and “The left fan-reverser [cowling] and 35 minutes before the beginning of tailpipe cone from the [no. 2 engine], the takeoff roll for the accident flight. as well as numerous small debris, Investigators determined that under the were found on and near the runway,” conditions of the previous flight, ice said the accident report by the Dutch ingestion could not be eliminated as Transport Safety Board. “Fan blade a possibility but was “very unlikely,” parts had penetrated the fan cowlings. the report said. A bird strike was On the underside of the right inboard considered impossible because visual

14 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 15 examination and a black-light inspec- adapter-ring failures, and in response tion of the fan blades, spinner cone the manufacturer had issued service and associated parts showed none of bulletins SB 71-73, SB 71-75 and SB the bird remains that would have been 71-76. In addition, the U.S. Federal found after such an event. Aviation Administration published a related airworthiness directive, AD “Between [the no. 2 engine] and the 75-12-03. rigid inlet duct of the pylon [to which the engine is attached], the tail-engine The report said, “According to the inlet adapter is installed to provide a manufacturer, it is known that condi- flexible coupling that compensates tions that may cause bellmouth [fail- for engine movement caused by flex- ures] and adapter-ring failures are: ing of the pylon structure,” said the • “Improper repair of the report. “The inlet adapter consists of a bellmouth/inlet-adapter-ring bellmouth attached to the front flange assembly; of the engine and an adapter ring attached to the lower vertical-stabilizer • “Engine no. 2 inlet ice ingestion rear-spar fireseal. The forward portion due to accumulation of snow of the bellmouth fits inside the ring to and ice during wintertime, FOD permit a sliding action between the [foreign object damage] and bird two parts.” strikes; • “Bellmouth and inlet-adapter The most probable cause of the engine ring not properly installed and failure, according to the report, was rigged; [and,] ingestion of parts of the bellmouth into the engine. • “Nonrepaired excessive bellmouth/inlet-adapter-ring The bellmouth assembly is supported delamination.” by 13 attachment brackets. On the accident engine, “nine brackets were No previous event involving bellmouth intact, from which six did not exhibit failure had led to complete ingestion distortion or other damage,” said the in the engine or an uncontained engine report. “From the remaining three in- failure, but ingestion of the bellmouth tact brackets, one suffered distortion, appeared to have occurred in this ac- one showed a crack and the last one cident, the report said. was gouged.” The report said, “It is evident that the The report said that the aircraft man- bellmouth failed at the joints between ufacturer had reported six events di- the brackets and honeycomb material, rectly related to bellmouth failures or which seems to be similar to earlier

16 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 17 events associated with bellmouth fail- (about seven months since [the] ures where bellmouth failure mode last overhaul of the aircraft and 10 was affected by an irregularity in the months since the last 2C inspection installation condition. … of the bellmouth and the adapter ring) the bellmouth panels were ripped off “It is believed that the bracket at from the brackets and were ingested the four o’clock position [forward into the engine. … looking aft] itself stayed intact, but the joint between the bracket and “The loose and distorted bracket the honeycomb material of the bell- found during the investigation sup- mouth probably had been weakened ports the thesis that improper instal- by influence of (normal) engine vi- lation was the initiating factor in this brations, movements due to throttle particular incident.” (power) transients and landings. It is likely that the joint of this particular The report did not prescribe any bracket eventually broke and caused remedial action on the grounds that the bellmouth to become unsupported proper installation and rigging of the in that position, thereby imposing bellmouth assembly were presented more load on the adjacent brackets adequately in existing service bul- and perpetuating the failure mode. letins, airworthiness directives and Finally, after 2,599 [flight] hours maintenance procedures.

NEWS & TIPS

Digital Video Recorder other video-based inspection equip- Stores Inspection ment, the manufacturer said. Video on Hard Disk Video images in the DV Sidekick are stored on a hard disk, available in The DV Sidekick from iShot Imag- 120-gigabyte (GB), 100-GB, 80-GB, ing is a lightweight, compact digital 60-GB and 40-GB models. Record- video recorder that can record up to 6.5 ing time is determined by hard-disk hours of inspection video at broadcast- capacity, frame rate and the compres- quality resolution, or more than 33 hours sion ratio, which is selectable between at maximum video-data compression, 4-to-1 and 20-to-1. Besides the stan- on the highest-capacity model. The dard television rate of 30 frames per recorder can be used with video probes, second (fps), rates as low as 2 fps can camera crawlers, pole cameras and be chosen for long-term monitoring.

16 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 17 The DV Sidekick can be clipped to an 200 pounds (91 kilograms) force. operator’s belt, worn on a neck strap, The contents of as many as 50 car- mounted on other equipment or set tridges, depending on the material’s up to be freestanding. Controls are viscosity, can be dispensed before located on a keypad that is integral the battery needs recharging, the with the recorder, which supports manufacturer said. both the NTSC and PAL formats. S-video inputs and outputs, as well as composite inputs and outputs, are available.

For more information: InterTest (the parent company of iShot Imaging), 303 Route 94, Columbia, NJ 07832 U.S. Telephone: +1 (908) 496-8008.

Hand-held Adhesive Dispenser Reduces Leakage

The EZ-mix HI Dispenser is a cordless electric hand-held adhesive dispenser that accommodates standard 50- Cordless Electric Hand-held milliliter (17-ounce) two-component Adhesive Dispenser cartridges. The dispenser is designed to significantly reduce leakage from the mix tip after the light-touch trig- For more information: DTIC Dispens- ger is released, said the manufacturer, ing Technologies, 835 Sterling Road, DTIC Dispensing Technologies. South Lancaster, MA 01561 U.S. Telephone: (877) 367-3842 (U.S.) or The dispenser features variable- +1 (978) 365-1884. speed control of its direct-current (DC) motor that allows the user to Drill Uses adjust the speed to the viscosity of Tangential Blades the material dispensed and the requirements of the application. The The KUB Duon drill from Komet has power supply is a six-volt nickel- exchangeable cutting blades that are metal-hydride (NiMH) battery pack. capable of drilling holes with a length- The motor can produce a maximum to-diameter ratio of as much as 5-to-1.

18 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 19 Tangential positioning of the blades action is required); low positive (there results in a high degree of stability is enough contamination to warrant during use, the manufacturer said. the application of biocide to fuel to kill the fungus); or high positive (there Cutting-blade diameters are available is serious contamination that requires in both English and metric measure- application of biocide and removal of ments, ranging from 0.828 inch to the microbial contamination from in- 1.156 inch (21.0 millimeters to 29.5 side the fuel tank). millimeters). Cutting-blade inserts are secured with clamping screws, For more information: Conidia Bio- which are designed for easy and fast science, Bakeham Lane, Egham, Sur- exchange of blades. Applications rey TW20 9TY England. Telephone: include cutting cast steel, cast iron, +44 (0)1491 829012. low-alloy steel, high-alloy steel and nonferrous metals. Fiber-optic System For more information: Komet of Bends Light America, 2050 Mitchell Blvd., Schaumburg, IL 60193 U.S. Tele- Aviation maintenance technicians phone: +1 (847) 923-8400. work in structural areas, fuel tanks and installations that are sometimes difficult to illuminate because of Kit Tests for obstructions or narrow openings. Aviation-fuel Fungus One tool designed to make viewing of confined spaces easier is the 3M Horoconis resinae, a microscopic High Intensity Fiber Optic Flashlight fungus, thrives in aviation fuel and System. can damage the linings of fuel tanks. Contamination of fuel by the fungus The system consists of a flashlight is particularly prevalent in tropical base to which is fitted the wide end environments or when aircraft spend of a cone, lined with reflective mate- an extended time in hangars. The rial to concentrate the light. Attached FUELSTAT resinae diagnostic kit to the narrow end of the cone is a from Conidia Bioscience offers a fast flexible fiber-optic tube, available in and convenient method to test for the seven-inch or 12-inch (18-centimeter presence of the fungus in kerosene or 30-centimeter) lengths. When the fuel samples, the manufacturer said. flashlight is powered, the fiber-optic tube is illuminated along its entire Results are classified as negative (there surface, with a high-intensity spot at is little or no contamination and no the tip.

18 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003 19 The flashlight, which uses AA-size Parts Cleaner Uses batteries, meets Underwriters Labo- Water-based Solution ratories (UL) specifications for use where flammable gases, vapors or PB10 and PB20 Parts Blasters from liquids exist, the manufacturer said. Peterson Machine Tool use a heated cleaning solution sprayed at 600 For more information: 3M Aerospace, pounds per square inch (42 kilograms 3M Center, Building 220-8E-05, St. per square centimeter) to strip away Paul, MN 55144 U.S. Telephone: grease and grime. The water-based (888) 364-3577 (U.S.) or +1 (651) solution has environmental-safety 737-7117. advantages and equal cleaning ef- fectiveness compared with solvents, the manufacturer said.

The cleaning machines have seven- day timers for energy conservation and temperature-controlling thermo- stats. Either a dual-fan or a “pencil” spray pattern can be selected to direct the spray. The cleaning solution is fil- tered so that the Parts Blaster can be used for final cleaning before assembly, the manufacturer said. Optional casters enable the units to be moved to different locations within the work area.

For more information: Peterson Machine Tool, 5425 Antioch Drive, Merriam, KS 66202 U.S. Telephone: High Intensity Fiber Optic (800) 255-6308 (U.S.) or +1 (913) Flashlight System 432-8970.

20 FLIGHT SAFETY FOUNDATION • AVIATION MECHANICS BULLETIN • MARCH–APRIL 2003

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