Airworthiness Directive · Amendment 39-11807 · Eurocopter Deutschland GmbH Model EC 135 Helicopters
Eurocopter Deutschland GmbH Model EC 135 Helicopters
Model EC 135 helicopters, certificated in any category.
Note 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment supersedes an existing airworthiness directive (AD) that applies to Eurocopter Deutschland GmbH (ECD) Model EC 135 helicopters. That AD requires conducting a tail rotor drive shaft vibration survey (survey), installing a Fenestron Shaft Retrofit Kit, inspecting each tail rotor drive shaft bearing (bearing) attaching lock plate for bent-open tabs and broken or missing slippage marks, and visually inspecting each bearing support for cracks. This AD requires conducting the survey and installing the Fenestron Shaft Retrofit Kit. This AD also requires installing double bearing supports and struts, revising the required compliance time for the repetitive inspections of the bearing attach hardware and supports, and removing the requirement to contact the FAA if a lock plate tab is bent open or if slippage marks are broken or missing. This amendment is prompted by continued reports of misaligned or cracked bearing supports and loose bearing attachment bolts. The actions specified by this AD are intended to prevent loss of drive to the tail rotor and subsequent loss of control of the helicopter.
To prevent loss of drive to the tail rotor and subsequent loss of control of the helicopter, accomplish the following:
(a) Before further flight, conduct a tail rotor drive shaft vibration survey and install a Fenestron Shaft Retrofit Kit L535M3002 882 in accordance with Eurocopter Deutschland GmbH Alert Service Bulletin (ASB) EC 135-53A-005, Revision 3, dated September 2, 1998.
(b) Before further flight, install double bearing supports for the tail rotor driveshaft and tail boom struts in accordance with ASB EC 135-53A-004, dated August 14, 1998.
Note 2: ASB EC 135-53A-002, Revision 2, dated September 2, 1998, pertains to the subject of this AD.
(c) Before further flight and thereafter at intervals not to exceed 50 hours time-in-service, perform the following:
(1) Clean each tail rotor drive shaft bearing support. Using a 6-power or higher magnifying glass and a bright light, visually inspect the attach lugs of the bearing supports B and C (shown in Figure 1) for cracks, particularly in the area extending from the bend radius to the attaching screws and rivets connecting the bearing supports to the tail boom. Before further flight, replace each cracked bearing support with an airworthy bearing support.
(2) Inspect each bearing attach hardware lock plate for bent-open tabs and slippage marks for attach hardware looseness or rotation. Before further flight, replace any loose bearing attach hardware (including lock plates found bent or open due to bolt rotation) with airworthy hardware.
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.
