Airworthiness Directive · Amendment 39-21112 · Main rotor gearbox
Airbus Helicopters (Previously Eurocopter France)
This AD applies to Airbus Helicopters (previously Eurocopter France) Model AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters, certificated in any category, with a main gearbox (MGB) lubrication pump (pump) part number 355A32-0700-01, 355A32-0700-02, or 355A32-0701-00, except helicopters with Modification (MOD) 077222 installed.
The FAA is superseding Airworthiness Directive (AD) 2008-24-04 for Eurocopter France (now Airbus Helicopters) Model AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters. AD 2008-24-04 required repetitively inspecting the lubricating pump and checking the magnetic chip detector plug (chip detector) and the main gearbox (MGB) oil-sight glass. This new AD retains the requirements of AD 2008-24-04 and allows the option of altering the MGB oil flow distribution as a terminating action for the inspections. This AD was prompted by an alteration developed by Airbus Helicopters of the MGB oil flow distribution that corrects the unsafe condition. The actions of this AD are intended to address an unsafe condition on these products.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) Before the first flight of each day and at intervals not to exceed 10 hours time-in-service (TIS), check the MGB magnetic chip detector plug (chip detector) for any sludge. Also, check for dark oil in the MGB oil-sight glass. The actions required by this paragraph may be performed by an owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD in accordance with Title 14 Code of Federal Regulations (14 CFR) §§ 43.9 (a)(1) through (4) and 14 CFR 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417, 121.380, or 135.439. “Sludge” is a deposit on the chip detector that is typically dark in color and in the form of a film or paste, as compared to metal chips or particles normally found on a chip detector. Sludge may have both metallic or nonmetallic properties, may consist of copper (pinion bearing), magnesium (pump case), and steel (pinion) from the oil pump, and a nonmetallic substance from the chemical breakdown of the oil as it interacts with the metal.
(i) Before further flight, if any sludge is found on the chip detector, remove, open, and inspect the pump.
(ii) Before further flight, if the oil appears dark in color when it is observed through the MGB oil-sight glass, take an oil sample. If the oil taken in the sample is dark or dark purple, before further flight, remove, open, and inspect the pump.
(2) Within 25 hours TIS, after operating both engines at normal operating revolutions per minute (RPM) for at least 20 minutes to ensure the MGB oil temperature has stabilized, inspect the oil pump for wear by following the Accomplishment Instructions, paragraph 2.B.2., steps 1. through 6., of Eurocopter Alert Service Bulletin (ASB) No. 05.00.51, dated July 9, 2007 (ASB 05.00.51), or Airbus Helicopters ASB No. 05.00.51, Revision 1, dated July 29, 2015 (ASB 05.00.51 Rev 1).
(i) Record the outside air temperature (OAT) and rotor speed (NR RPM) and plot the point at which they intersect using the graph in Figure 1 or 2 of ASB 05.00.51 or ASB 05.00.51 Rev 1.
(ii) If the point on the graph at the intersection of the recorded OAT and the NR RPM falls within:
(A) Zone 3—Before further flight, replace the MGB and pump with an airworthy MGB and pump.
(B) Zone 2—At intervals not to exceed 25 hours TIS, repeat the inspection procedures by following the Accomplishment Instructions, paragraph 2.B.2, steps 1. through 6., of ASB 05.00.51 or ASB 05.00.51 Rev 1. After being classified in “Zone 2,” you must obtain two successive inspections separated by at least 24 hours TIS that fall within Zone 1 before you can begin to inspect at intervals not to exceed 110 hours TIS by following paragraph (f)(2)(ii)(C) of this AD for Zone 1.
(C) Zone 1—At intervals not to exceed 110 hours TIS, repeat the inspection procedures by following the Accomplishment Instructions, paragraph 2.B.2., steps 1. through 6., of ASB 05.00.51 or ASB 05.00.51 Rev 1.
(iii) Compliance with paragraphs (f)(2)(i) and (ii) of this AD constitutes terminating action for the checks and inspections required by paragraph (f)(1) of this AD.
(3) As an optional terminating action for the requirements in this AD, alter the lubrication system for the MGB in accordance with the Accomplishment Instructions, paragraphs 3.B.2.a. through 3.B.3 of Airbus Helicopters Service Bulletin No. AS355-63.00.25, Revision 1, dated July 29, 2015, or Revision 2, dated June 22, 2017. Mineral oil 0-155 is required after compliance with this alteration.
Note 1 to paragraph (f)(3) of this AD: Airbus Helicopters identifies alteration of the lubrication system as MOD 077222.
