Airworthiness Directive · Amendment 39-17552 · Main rotor gearbox
Eurocopter Deutschland GmbH Helicopters
Superseded. A later AD replaced this one: AD 2018-07-01. Comply with the one in force.
This AD applies to Eurocopter Deutschland GmbH Model EC135 P1, P2, P2+, T1, T2, and T2+ helicopters with a main transmission FS108 housing upper part, part number (P/N) 4649 301 034 and a serial number listed in Table 1 of Eurocopter Alert Service Bulletin EC135-63A-017, Revision 0, dated October 11, 2010 (ASB EC135-63A-017), certificated in any category.
We are adopting a new airworthiness directive (AD) for all Eurocopter Deutschland GmbH (ECD) EC 135 P1, P2, P2+, T1, T2, and T2+ helicopters equipped with a certain main transmission housing upper part. This AD requires installing a corrugated washer in the middle of the main transmission filter housing upper part and modifying the main transmission housing upper part. This AD was prompted by an inspection of housing upper parts that revealed the bypass inlet in the oil filter area was not manufactured in accordance with applicable design specifications. The actions of this AD are intended to prevent failure of the main transmission and subsequent loss of control of the helicopter.
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) Within 3 months, remove the oil filter element and install a corrugated washer, P/N 0630100377, in the middle of the filter housing of the housing upper part as depicted in Figure 2 of ASB EC135-63A-017.
(2) Within 4,000 hours time-in-service or at the next main transmission repair or overhaul, whichever occurs first, machine the main transmission housing upper part in accordance with Annex A of ZF Luftfahrttechnik GmbH Service Instruction No. EC135FS108-1659-1009, dated September 14, 2010.
(3) Do not install a main transmission upper part, P/N 4649 301 034, on any helicopter unless it has been modified as required by paragraphs (e)(1) through (e)(2) of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
