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Home , Boeing 747, Boeing 747SP, El Al

Out with the old, in with the new

The retirement of ageing early-series 747s is freeing maintenance capacity that can now be used to meet the increasing needs of later variants, which are beginning to reach maturity, albeit with less demanding maintenance requirements than their predecessors. Ian Goold investigates

angar space used for around 250 will be accommodated by the capacity 747-400 D checks are expected to [take fewer] Boeing 747SP, -100, -200, and vacated by retiring 747 Classics,” says than 25 days.” H -300 Classics is being shared Boeing Commercial maintenance- By 2015-16, about 111 such D checks a year with younger 747-400s that are subject to economics director Khwaja Ali. “The older will be performed on 747-400s, up a sixth on less intensive maintenance. “More D checks 747s take significantly longer time in D checks the 95 typically carried out annually since 2005, on 747-400s delivered in the past five years due to their ageing, whereas the newer according to Ali. “We need to account for longer

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(photo: Technik)

[maintenance] duration in the third D checks, events. “boeing has off ered Classic operators and the need for more hangar capacity, but which start occurring in [the coming fi ve years]. an MSG-3 programme that reduces average boeing analysis shows that accelerated Viewed alone, it would indicate a need for 25% D check time by eliminating many tasks and retirement of older 747s – more for fuel burn additional 747 hangar capacity, but the [space] extending many intervals,” says Ali. “The efficiency than higher maintenance costs – being vacated by accelerated retirement of non-routine fi ndings continued to grow due frees more hangar space than is lost to 747 Classics easily absorbs this demand.” to ageing, [but] the net result was still a D check time escalation. The 747-400’s unique calendar-driven reduction in D check [time of] about fi ve days Of the 959 active boeing 747s (as at December inspection schedule means that peaks and – freeing about 5% of hangar capacity.” 2010), some 29.5% – or 283 units – are Series troughs in MRO demand are not influenced The revised maintenance programme has 200s or 300s, which are being retired at a rate of by different usage among operators. been available since 2002, with boeing saying 37 a year. The fl eet is expected to decline to 818 D check requirements will be largely that it has given participating operators over the next six years, says Ali. governed by delivery dates (and rates), with reduced maintenance labour-hours, as Since entering service with Northwest calendar frequency determined by the well as increased aircraft availability. “The in January 1989, the 747-400 has seen maintenance programme. programme provides fl exibility to operators a steady increase in scheduled maintenance to package tasks based on their business intervals, with myriad improvements and Reduced requirements requirements and can vary.” modifi cations extending and engine Since boeing instituted a revision of inspection Ali suggests it would be reasonable to life, as well as reducing overhaul costs. Initial requirements for all 747 series aircraft, using suppose that the ageing of the 747 Classics scheduled requirements were: A check at 300 uS Air Transport Association Maintenance fleet implies that hangar downtime for fl ight hours (FH), C check at 15 months (but Steering Group Level 3 (MSG-3) standards D checks increases by 50% for third (and not to exceed 3,000FH), and D check at fi ve about 10 years ago, two signifi cant trends have subsequent) D checks, compared with a years (but not to exceed 25,000FH). emerged: lower D check downtime and 747-400’s first two such inspections. The The model’s maintenance review board reduced frequency of heavy maintenance longer time implies a more expensive job (MRb) has increased Maintenance Planning

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Data document (MPD) intervals to: A check 21 months, and D checks every six years, 1,000FH, C check 24 months (but not to exceed although it has now adopted the MRB/MPD 10,000FH), and D check eight years, explains programme with the exception of the C check BCA maintenance-engineering director Larry 10,000FH restriction. The German MRO performs Slate. After two D checks (D1 and D2), eight-year 12 747-400 D checks per year on a single line, inspections become six-year inspections for says D2 or D3 checks should require 40 to 45 relevant structures. days, and at the beginning of 2011 still had slots Ali points out that not all interval available in the middle of the year. improvements arose from MPD changes: “In maintenance provider many cases, lead operators were supported Technical (EAT), whose parent group to analyse and increase their check intervals operates seven 747-400s (including one based on their own experience”. He says that freighter) with an average age of 10 years, the current 747-400 inspection schedule and has not adjusted its inspection schedule over escalation of individual intervals implies a 15% time, according to information provided by reduction in scheduled tasks over the life of maintenance-marketing manager Eli Uziel, an aircraft and a corresponding reduction of aircraft overhaul-division production-service about 5% in hangar space demand. manager Moshe Tabib, maintenance-specifi- cation manager Shaul Peri, and aircraft-structure, Alternative approaches Interior, and non-destructive testing engineering Different operators or MRO providers may use manager Oren Jerasi. LHT confirms an industry trend for D checks to take place in , where manhour rates are different schemes, according to a small random EAT has adopted C check intervals of much lower than elsewhere. It is the main source survey by MRO Management. For example, in 16,000FH (or 18 months – whichever comes of European C check capacity following AFI KLM E&M’s decision to drop such maintenance , the (LHT) schedule first) and D checks every 25,000FH (or 72 (photo: Lufthansa Technik) involved A checks every 700FH, C checks every months), and has performed about 10 D checks

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– including one third-party contract for a foreign How is the -800 expected to compare? carrier. The MRO schedules “approximately 15 days (around 13,000 hours)” for full C checks and 25 or 50 days (around 27,000 hours), respectively for partial or full D checks. This year’s slots are sold out and it is accepting enquiries for 2012. Before the parent company grounded its fleet of one 747-300 and three -400s as an economy measure, the technical division of (SAA) divided A check, 650FH-interval work into two separate maintenance jobs: the airframe check (CKA) plus weekly engine items, and the engine (photo: Boeing) check (CKE) plus weekly airframe items. C checks were performed every 6,500FH, or Boeing concedes that since the new 747-800 (marketed as the 747-8) is a larger aircraft than 18 months, and D checks at a maximum of the current 747-400 (an extra 51 seats and an 18ft longer ), its maintenance costs six-year intervals. would normally be expected to be higher. “However, due to system, structural, and SAA Technical has capacity for up to four maintenance-programme improvements, the airframe maintenance cost is expected to 747 D checks a year, with no current backlog. be 3% lower than that of the -400,” says Boeing Commercial Airplanes maintenance- One 747-400 still in service was due for a economics director Khwaja Ali. “Technology improvements reduce cost by 5% and C check in March 2011and a D check in July maintenance programme by 3%. Size (weight and passengers) increases cost by 4% for [a] next year. Aircraft not in operation are subject net cost reduction of 3%”. to weekly checks and SAA has carried out

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third-party work for Lufthansa, ’s What’s your Powering improvement Kingdom Holding, Saudi Arabian Airlines and TAAG Angola Airline. Scheduled maintenance for the 747-400 is Owners and operators of the Boeing personal generally similar for all sub-variants, with some 747-400 have benefitted from differences on systems-inspection requirements improvements to each of the three offered based on production improvements and engines, as well as airframe and systems service-bulletins (SBs) or modifications. Although maintenance requirements, according best?... system and structure SBs have been raised to to Boeing improve 747-400 performance, these have not had a significant impact on scheduled Rolls-Royce RB211-524 – in 1998, maintenance, according to BCA maintenance Rolls-Royce incorporated Trent engine engineering director Larry Slate, who confirms technology and upgraded the RB211-524’s that incorporation of relevant bulletins can allow high-pressure compressor (HPC), some tasks to be eliminated or some intervals combustor, and HP turbine (HPT) to to be increased. produce the ‘-T’ variant. Boeing says that Continuous improvements in materials and this resulted in a “significant increase” in corrosion-prevention measures have contributed exhaust-gas temperature (EGT) margin to the escalation of 747-400 structural inspection and decreased shop maintenance. The intervals from six to eight years. “Operations- powerplant manufacturer also introduced (photo: Lufthansa Technik) performance data and subsequent analysis fan-blade modifications to decrease have resulted in optimisation of scheduled inspection and lubrication maintenance requirements and increase blade life by 67%. A maintenance [requirements],” according to Slate. new compressor drum standard introduced in 2006 increased the component life by 43%. AkzoNobel Aerospace Coatings are bringing “All corrosion-prevention and control-programme consistent, reliable quality to the Base Coat/ (CPCP) work mandated by airworthiness directives Pratt & Whitney PW4000 – Boeing says that the PW4000-94-inch advantage performance Clear Coat arena. The all new Aerodur© (ADs) were incorporated with re-analysed MRB upgrade (APU) kit, covered by a September 2010 service bulletin, has been developed to Base Coat/Clear Coat system provides a structural- and zonal-programme requirements.” provide up to 1% fuel savings and significant HPT-durability improvement. The kit cost effective solution for every paint shop This produced a streamlined baseline programme represents targeted technology insertion from the PW4000-100-inch ADV70 engine. that wants to produce top-quality fi nishes that has eliminated overlapping and duplicate The durability improvements include a 1/2K thermal-barrier ceramic, new blade outer air with a faster turnaround, allowing you to set maintenance requirements, and has also seen seals, reduced first- and second-stage HPT blade clearance, and increased second-stage record process times. incorporation of SFAR88 requirements into blade cooling flow. the schedule. Annual delivery rates of the 747-400 have General Electric (GE) CF6-80C2 – GE’s continuing engineering focus is on areas such as fluctuated in response to airline demand, which Tech CF6 HPT blades, enhanced compressor technology, and thrust-reverser system- in turn follows passenger traffic trends that reliability improvements that reduce cost of ownership and maintenance requirements 3001 Base Coat typically follow (and, in fact, exaggerate) swings and increase reliability and durability, says Boeing. “The CF6-80C2’s time-on-wing has 3002 Clear Coat in global economic trends. Deliveries have continued to grow 6% a year since 1992 and averages about 13,000 hours for a mature varied from over 60 in the early , through shop visit. [It] combines a proven core with the latest technical innovations to offer the 30 or less in the middle years of the last decade, highest reliability, longest life, and lowest fuel burn in its thrust class.” • Can save up to 30% process time to much lower rates more recently. Indeed, Ali • Extends durability confirms that in the past five years, just 65 have • Provides high gloss and color retention been delivered – scarcely more than one a month. “The first of these will start coming in Geographical distribution He explains that “for reasons other than for D checks after eight years, in 2013.” But will maintenance demand be global or capacity” 747-400s are typically flown to low Boeing’s calendar-based heavy-maintenance regional. And how balanced are regional labour cost areas for D checks, other major work, schedule means that cycles in demand for capacity demand and supply? And what and modifications. LHT confirms an industry D check capacity will reflect those in deliveries, factors drive regional differences? “There is trend for D checks to take place in Asia, where www.akzonobel.com/aerospace with Ali reporting plenty of overall MRO sufficient capacity for 747-400 D checks in “manhour rates are much lower than elsewhere. capacity. There was sufficient capacity for the all regions,” says Ali. “Most [aircraft] are in Asia United, for example, is sending [its] complete estimated 150 D checks in 2010, and the Pacific, with the second largest concentration fleet to Ameco” in . Under a five-year additional 13 aircraft expected in each year from in western Europe.” Nevertheless, south Asia contract agreed in March 2010, United’s 747s 2013 is equivalent to demand for slightly less remains short of MRO capacity for large began to go to Ameco Beijing last October for than a two-bay hangar. The increase in required machines, says Ali: “Infrastructure has not heavy maintenance and C checks, with the capacity will be offset by that left vacant by 37 been able to keep pace with the [region’s] MRO also performing maintenance and cabin Classics being retired each year. burgeoning growth.” upgrades on the US carrier’s Boeing 777s.

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Signifi cant tasks and service bulletins

With boeing 747-400 development benefi tting from myriad y Fuel-jettison wiring; improvements and modifi cations, Lufthansa Technik (LHT) lists more y Emergency locator transmitter (ELT); than 1,000 service bulletins (Sbs), many of which have had an impact y 8.33kHz radio-frequency channel spacing; on operational reliability and maintenance costs. The German MRO y Integrated drive generator (IDG) power feeder cable; and identifi es the most signifi cant tasks: y Pylon leading-edge wiring. y 747-53A2507/airworthiness directive (AD) 2077-23-18 – stretched Regular work in recent years for El Al Technical has been upper-deck tension-tie inspection and repair; modifi cation of overhead crew rest areas above Door 5, a y 747-54A2218/AD 2005-19-09 – DSb underwing mid-spar fi tting 150-manhour exercise carried out during C checks. In 2008-09, inspection and modifi cation; it introduced a cabin-upgrade programme to replace premium- y 747-53A2563 – scribe line inspection; class seats and to install power points in the economy-class y 747-53A2784 – bS320 crown-frame web inspection sections. In-fl ight entertainment systems were also enhanced, and replacement; while the package also included new seat fabrics, carpets y 747-57A2331 – wing landing-gear support-beam end fi tting; and curtains. y Ageing safety rule; beyond the crew rest area AD, El Al sees most such mandatory y Widespread fatigue damage rule; and work as structural strengthening of the aircraft. The uS SFAR88 y Supplemental structural-inspection document (SSID) programme. requirement (introduced following the TWA Flight 800 accident) Asked about the most signifi cant, or critical, 747-400 Sbs (those was regarded as a ‘’ issue that required a lot of manhours, a most frequently specifi ed in third-party maintenance contracts) and sentiment that has been echoed by LHT. by the time a 747-400 ADs, SAA Technical nominates these modifi cations: receives its second C check (C2), about 40% of MRO activity is y Cockpit door surveillance; non-routine, says El Al. A typical example of such non-major y Enhanced ground-proximity warning systems (EGPWS); maintenance is CPCP work in the compartment.

Ali says that any spare hangar capacity to Ali. “Improvements have come from regular by the number of mechanics available, the released elsewhere by 747-400s going to Asia product [development], better support in quality of their training, and the availability Pacific for maintenance is being used by spares, and [the] increased experience of airlines of spares. smaller aircraft that cannot fly to lower-cost and technical departments.” Others are: “the extent and quality of repairs areas. LHT sees a lack of European C check boeing says that variation in schedule performed during overnight maintenance [and] capacity, with its own facilities comprising reliability among operators may be due to a the extent [to which] the airline uses its despatch- the main supply following AFI KLM E&M’s number of factors, including stage-length deviation guide”. In LHT’s experience, 747-400 decision to drop such maintenance. SAA differences and daily utilisation. Ali points reliability – “as usual for commercial aircraft” – Technical expects global maintenance out that one consideration is the speed of initially dropped and then increased before capacity will be reduced “due to the declining aircraft turnaround, since longer times permit subsequently decreasing as the airframe and 747 market”. more maintenance, which in turn is driven components have matured.

Reliability How has despatch-reliability performance evolved as the 747-400 has matured, and do these improvements vary between operators? In 2008, boeing told MRO Management that, as the fl eet had matured, reliability had remained “fairly stable [at] between 98.4% and 98.6% over many years”. Now, schedule reliability has improved to around 99%, as measured during the 12 months from November 2009 to October 2010, according

El Al Technical has performed about 10 D checks – including one third-party contract for a foreign Meet us at carrier. This year’s slots are sold out and it is MRO accepting enquiries for 2012 (photo: El Al Technical) Miami/April 12-14 Stand 2413

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LHT says that the most recent MRB report No significant structural cracking within 20,000-cycle DSO revision was in May 2009, when letter checks were optimised, with temporary revisions To stay ahead of the most active (or oldest) airframes, Boeing continuously evaluates fleet following in December 2009 and July 2010 to reports for potential improvements that can be incorporated into new production aircraft meet the requirements of FAA Advisory Circular or additional maintenance actions for in-service machines. “The 747-400 is a derivative of 25-27 using the MSG-3 enhanced zonal the original 747 [that] is proven by static- and fatigue-test data, as well as fleet data,” says the procedure (EZAP). The MRO says that the D check manufacturer. For validation of the redesigned “Section 41” forward fuselage – modified escalation represents the latest maintenance after structural-cracking problems with early airframes and now the “baseline” for the development from the 747-400 industry steering 747-400 – Boeing has carried out additional fatigue testing. “This demonstrated no committee (ISC). According to Boeing’s Slate, significant cracking [ahead of the 20,000-cycle] design service objective (DSO) [but] did there are currently no “major” changes being define maintenance actions and inspections for airplanes operating past the DSO.” considered by the ISC. In addition, Boeing has conducted tear-downs of a 747-100 and a 747-400 forward- When the 747-400 was designed in 1986-87, fuselage fatigue-test article, which (with the extra testing) has been used to define direct maintenance costs (DMCs) at entry into maintenance actions or inspections. “Boeing has issued further service action to instruct service (EIS) were foreseen as being 10% lower operators of high-cycle or high-hour 747-400s to remove fasteners from specific critical than those of the 747-200, but in practice were structural joints, perform intensive inspections, and report any findings toB oeing.” As of actually 26% less. The 747-400 airframe January 2011, there had been no significant findings from these inspections to generate maintenance cost has been as expected and in additional fleet action. cents/available seat-mile basis is “among the Boeing says that the DSO is a concept useful for assessing the economics of airplane best of all airplanes”, claims Ali. structural maintenance: “Continued airworthiness up to, and beyond, the DSO is assured by effective scheduled maintenance and compliance with mandatory actions.” The cost of ageing The 747-400’s 20-year, 20,000 flight-cycle DSO may be summarised as the minimum How have DMCs for mature 747-400s compared period of service during which at least 99% of primary structural details (or 955 over 30 with expectations, and how will these change years) remain free of detectable fatigue cracks with 95% confidence.B oeing has subjected as the fleet ages further? “As airplanes age, we the 747-400 complete-airframe fatigue-test specimen to 20,000 cycles, with the fuselage expect the 747-400 maintenance cost to grow receiving 20,000 additional pressure cycles, while the forward-fuselage Sections 41 and 42 above the mature maintenance cost after the have undergone a further 20,000 pressure-test cycles. The manufacturer says that the second D check by about 3% per year,” explains 747-400’s airframe structure is designed “to exceed the DSO with modest increase in Ali. “This is without accounting for any inflation maintenance costs”. in material or labour costs. So, a 25-year-old airplane would cost about 30% more to maintain than a mature airplane younger than 15 years.” Meanwhile, Boeing is charting mature from increased competition as additional MRO programmes (such as check or limit escalation) 747-400 airframe maintenance costs, which are players have entered the component overhaul/ that have helped to keep costs in line with internal said to be reducing by 0.5% per year. “During repair business. targets. However, this is offset by the potential the last 15 years, mature maintenance cost (as LHT confirms that DMCs may be managed, for other airframe problems to develop. measured between the first two D checks) has and that increases are not inevitable. “[Such “The 747-400 is a challenging aircraft reduced by 7% from what was initially costs] can be controlled as cost-increasing factors concerning DMCs as several structural items modelled,” says Ali. [such as] ageing are reduced, or even equalised are developing over the period,” warns LHT; “The reduction is due to a combination by applying ‘Lean’ methods in maintenance or both LHT and SAA Technical benchmark their of product improvement, check interval setting up reliability programmes.” 747-400 maintenance costs against those of improvements, and better product support.” In recent years, the MRO and sister company competing MROs through analysis of industry Further cost reductions have “usually” resulted Lufthansa have introduced improvement media publications.

Boeing 747-400 fleet* and fleet leaders

Orders 694; Deliveries 671; Backlog 23 Category Delivery Age Cycles Hours Oldest aircraft 26/01/89 21.9 years 11,876 91,024 Aircraft with most flight cycles 13/10//92 18.2 years 32,047 43,461 Aircraft with most flying hours 26/10/89 21.2 years 13,971 110,041 *As at January 2011 (source: Boeing)

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