§ 33.37 14 CFR Ch. I (1–1–14 Edition)

applicant must show that foreign par- § 33.42 General. ticles passing through the prescribed Before each endurance test required filtering means will not critically im- by this subpart, the adjustment setting pair engine fuel system functioning. and functioning characteristic of each (d) Each passage in the induction sys- component having an adjustment set- tem that conducts a mixture of fuel ting and a functioning characteristic and air must be self-draining, to pre- that can be established independent of vent a liquid lock in the cylinders, in installation on the engine must be es- all attitudes that the applicant estab- tablished and recorded. lishes as those the engine can have [Amdt. 33–6, 39 FR 35465, Oct. 1, 1974] when the aircraft in which it is in- stalled is in the static ground attitude. § 33.43 Vibration test. (e) If provided as part of the engine, (a) Each engine must undergo a vi- the applicant must show for each fluid bration survey to establish the tor- injection (other than fuel) system and sional and bending vibration character- its controls that the flow of the in- istics of the crankshaft and the pro- jected fluid is adequately controlled. peller shaft or other output shaft, over [Doc. No. 3025, 29 FR 7453, June 10, 1964, as the range of crankshaft speed and en- amended by Amdt. 33–10, 49 FR 6851, Feb. 23, gine power, under steady state and 1984] transient conditions, from idling speed to either 110 percent of the desired § 33.37 Ignition system. maximum continuous speed rating or Each spark ignition engine must 103 percent of the maximum desired have a dual ignition system with at takeoff speed rating, whichever is high- least two spark plugs for each cylinder er. The survey must be conducted and two separate electric circuits with using, for airplane engines, the same separate sources of electrical energy, configuration of the propeller type or have an ignition system of equiva- which is used for the endurance test, lent in-flight reliability. and using, for other engines, the same configuration of the loading device § 33.39 Lubrication system. type which is used for the endurance test. (a) The lubrication system of the en- (b) The torsional and bending vibra- gine must be designed and constructed tion stresses of the crankshaft and the so that it will function properly in all propeller shaft or other output shaft flight attitudes and atmospheric condi- may not exceed the endurance limit tions in which the airplane is expected stress of the material from which the to operate. In wet sump engines, this shaft is made. If the maximum stress requirement must be met when only in the shaft cannot be shown to be one-half of the maximum lubricant below the endurance limit by measure- supply is in the engine. ment, the vibration frequency and am- (b) The lubrication system of the en- plitude must be measured. The peak gine must be designed and constructed amplitude must be shown to produce a to allow installing a means of cooling stress below the endurance limit; if the lubricant. not, the engine must be run at the con- (c) The crankcase must be vented to dition producing the peak amplitude the atmosphere to preclude leakage of until, for steel shafts, 10 million stress oil from excessive pressure in the reversals have been sustained without crankcase. fatigue failure and, for other shafts, until it is shown that fatigue will not occur within the endurance limit stress Subpart D—Block Tests; of the material. Reciprocating Aircraft Engines (c) Each accessory drive and mount- ing attachment must be loaded, with § 33.41 Applicability. the loads imposed by each accessory This subpart prescribes the block used only for an aircraft service being tests and inspections for reciprocating the limit load specified by the appli- aircraft engines. cant for the drive or attachment point.

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