Airworthiness Directive · Amendment 39-17774 · Main rotor gearbox
Eurocopter Deutschland GmbH Helicopters
This AD applies to Model EC135P1, EC135P2, EC135P2+, EC135T1, EC135T2, and EC135T2+ helicopters with a main gearbox (MGB), part number (P/N) 4649 010 003, 4649 010 005, 4649 010 006, 4649 010 006X, 4649 010 008, 4649 010 008X, 4649 001 007, 4649 010 010, or 4649 010 013 installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for Eurocopter Deutschland GmbH (Eurocopter) Model EC135P1, EC135P2, EC135P2+, EC135T1, EC135T2, and EC135T2+ helicopters. This AD requires analyzing the main gearbox (MGB) oil for indications of metal chips or pieces, reviewing the MGB log or equivalent record, and inspecting certain teeth in the MGB after two chip indications. This AD was prompted by a partial tooth rupture found in an MGB that was returned to the manufacturer for repairs. The actions of this AD are intended to detect wear in the MGB that could lead to a gear tooth rupture, failure of the MGB, loss of power to the main rotor, 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 100 hours time-in-service (TIS), and thereafter at intervals not to exceed 100 hours or 12 months, whichever occurs first, take an oil sample in accordance with the Accomplishment Instructions, Part 1, of Eurocopter Alert Service Bulletin EC135-63A-012, Revision 5, dated September 6, 2011 (ASB EC135-63A-012).
(2) Within 25 hours TIS after taking the oil sample in paragraph (e)(1) of this AD, analyze the oil sample in accordance with the Accomplishment Instructions, Part 2.A. through Part 2.C. of ASB EC135-63A-012, except that you are not required to contact Eurocopter.
(i) If the analysis indicates Stage II as specified by the Accomplishment Instructions, Part 2.B., of ASB EC135-63A-012, within 25 hours TIS, remove and inspect the oil filter element for a chip, defined as any solid piece of metal but not metallic fuzz or fine particles.
(A) If there are no chips, clean the oil filter element and chip detector, inspect the drive stage toothing, perform a ground run, and inspect for leaking oil in accordance with the Accomplishment Instructions, Part 4.A through 4.G, of ASB EC135-63A-012. Change the oil.
(B) If there is a chip, replace the MGB with an airworthy MGB before further flight.
(ii) If the analysis indicates Stage III as specified by the Accomplishment Instructions, Part 2.B., of ASB EC135-63A-012 and if the water content is between 0.1 and 0.5 percent, within 10 hours TIS, remove and inspect the oil filter element for a chip.
(A) If there are no chips, clean the oil filter element and chip detector, inspect the drive stage toothing, perform a ground run, and inspect for leaking oil in accordance with the Accomplishment Instructions, Part 4.A through 4.G, of ASB EC135-63A-012. Change the oil.
(B) If there is a chip, replace the MGB with an airworthy MGB before further flight.
(3) Before the MGB has accumulated 300 hours TIS, determine whether two or more chip indications have occurred. If two or more chip indications have occurred, inspect the drive stage toothing, perform a ground run, and inspect for leaking oil in accordance with the Accomplishment Instructions, Part 4.A through 4.G, of ASB EC135-63A-012.
(4) Any time there is a chip indication, remove and inspect the chip detector for deposits (fine particles or metallic fuzz) or chips, and remove and inspect the oil filter element for a chip.
(i) If there are no chips and a minimal amount of particles or metallic fuzz, corresponding to Figure 5, Stage A of ASB EC135-63A-012, clean the chip detector and the oil filter element and enter the chip indication on the MGB log card before further flight.
(ii) If there are no chips and some particles or metallic fuzz, corresponding to Figure 5, Stage B of ASB EC135-63A-012, clean the chip detector and the oil filter element and enter the chip indication on the MGB log card before further flight, and within 10 hours TIS inspect the drive stage toothing, perform a ground run, and inspect for leaking oil in accordance with the Accomplishment Instructions, Part 4.A through 4.G, of ASB EC135-63A-012. Perform a ground run for 15 minutes at the flight-idle power setting, and then re-inspect the chip detector for a chip, particles, and metallic fuzz.
(iii) If there is a chip, replace the MGB with an airworthy MGB.
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.
