Airworthiness Directive · Amendment 39-17545 · Tail rotor gearbox
Eurocopter France Helicopters
This AD applies to Eurocopter France (Eurocopter) models AS332C, AS332L, AS332L1, AS332L2, and EC225LP helicopters, serial numbers (S/N) up to and including 2680 and S/N 9000 through 9009, certificated in any category.
We are adopting a new airworthiness directive (AD) for certain Eurocopter France (Eurocopter) Model AS332C, AS332L, AS332L1, AS332L2, and EC225LP helicopters to require inspecting for the presence of blind holes in the tail gearbox (TGB) attachment fittings, and, if they are missing, installing an additional washer under the head of the attachment bolt until the attachment fitting is replaced with an airworthy attachment fitting. This AD was prompted by the discovery of interference between the TGB aft attachment bolt and the structure fitting, caused by a manufacturing anomaly that omitted the blind hole required for proper fit of the attachment bolt. This condition, if not detected and corrected, could result in insufficient tightening of the TGB casing, damage to the TGB attachment, cracking under the attachment bolt, and loss of the TGB, resulting in 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.
Within 50 hours time-in-service (TIS):
(1) Inspect the TGB aft attachment fitting to measure the dimension for a blind hole as follows:
(i) Remove the TGB attachment bolt (c) but retain washer (d) as depicted in Detail A, Figure 1, of Eurocopter Emergency Alert Service Bulletin (EASB) No. 53.01.58 and EASB No. 53A012, both Revision 1, and both dated January 4, 2008.
(ii) Use a depth gauge to measure dimension “x” between the top face of the washer (d) and the bottom of aft fitting (a) as depicted in Detail A, Figure 1, of the EASB.
(2) If the measurement is equal to or greater than 81 mm, then the blind hole is present. Install the TGB attachment bolt (c) with its washer (d) as depicted in Detail A, Figure 1, of EASB No. 53.01.58 or No. 53A012. Lock with lockwire.
(3) If the measurement is less than 81 mm, then the blind hole is missing. Inspect the end of the threaded section of bolt (c) for chafing or a contact mark, as depicted in Area 1, Figure 1, of the EASB.
(i) If there is no chafing and no contact marks, install bolt (c) with washer (d) and additional washer (2) as depicted in Detail B, Figure 1, of EASB No. 53.01.58 or No. 53A012.
(ii) If there is chafing or a contact mark, replace the TGB attachment bolt (c) with an airworthy bolt and install with washer (d) and additional washer (2) as depicted in Detail B, Figure 1, of EASB No. 53.01.58 or No. 53A012. Lock with lockwire.
(iii) Within the next 825 hours TIS, replace the TGB aft attachment fitting with an airworthy attachment fitting.
(4) Inspect the right and left attachment points of the TGB forward attachment to measure the dimension for a blind hole, as follows:
(i) Remove both TGB attachment bolts (c) but retain washers (d), as depicted in Detail A, Figure 2, of EASB No. 53.01.58 or No. 53A012.
(ii) Use a depth gauge to measure dimension “x” between the top face of washer (d) and the bottom of forward fitting (b) at the right and left attachment points, as depicted in Detail A, Figure 2, of EASB No. 53.01.58 or No. 53A012.
(5) If both measurements are equal to or greater than 81 mm, then the blind hole is present. Install TGB attachment bolt (c) with its washer (d), as depicted in Detail A, Figure 2, of EASB No. 53.01.58 or No. 53A012. Lock with lockwire.
(6) If one or both measurements are less than 81 mm, then the blind hole is missing. Inspect the end of the threaded section of each bolt (c) for chafing or a contact mark, as depicted in Area 1, Figure 2 of EASB No. 53.01.58 or No. 53A012.
(i) If there is no chafing and no contact marks, for each attachment point, install bolt (c) with washer (d) and additional washer (2), as depicted in Detail B, Figure 2, of EASB No. 53.01.58 or No. 53A012.
(ii) If there is chafing or a contact mark, replace each the TGB attachment bolt (c) with an airworthy bolt and install bolt (1) with washer (d) and additional washer (2), as depicted in Detail B, Figure 2, of EASB No. 53.01.58 or No. 53A012. Lock with lockwire.
(iii) Within the next 825 hours TIS, replace the TGB forward attachment fitting with an airworthy attachment fitting.
