Airworthiness Directive · Amendment 39-18317 · Tail rotor drive
Sikorsky Aircraft Corporation (Type Certificate Previously Held by Schweizer Aircraft Corporation)
This AD applies to Sikorsky Aircraft Corporation (Sikorsky) Model 269A, 269A-1, 269B, 269C, 269C-1, 269D, and TH-55A helicopters, certificated in any category.
We are adopting a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model 269A, 269A-1, 269B, 269C, 269C-1, 269D, and TH-55A helicopters. This AD requires repetitively inspecting and lubricating the tail rotor (T/R) driveshaft splined fittings. This AD was prompted by a report that the T/R driveshaft can disconnect due to deterioration of the splined coupling. The actions are intended to detect and prevent excessive wear of the splined coupling, which could lead to failure of the T/R driveshaft 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):
(i) Inspect each T/R driveshaft splined fitting for a crack, a break, excessive wear, galling, spalling, chipping, corrosion, heat discoloration, and distortion by following the Accomplishment Instructions, paragraphs 3.B.(1) through 3.B.(2), of Sikorsky 269 Alert Service Bulletin (ASB) B-299.1 for Model 269A, 269A-1, 269B, 269C, and TH-55A helicopters; 269C-1 ASB C1B-036.1 for Model 269C-1 helicopters; or 269D ASB DB-041.1 for Model 269D helicopters, each Revision 1 and dated February 24, 2012. If there is a crack, a break, excessive wear, galling, spalling, chipping, corrosion, heat discoloration, or distortion on any T/R driveshaft splined fitting, before further flight, replace the affected splined fitting and the T/R driveshaft.
(ii) If installed, inspect each T/R driveshaft grease fitting for looseness, presence of a check ball inside each fitting, and for proper operation and seating of each check ball. If any grease fitting is loose, missing a check ball, fails to properly operate, or if a check ball fails to seat, before further flight, replace the grease fitting.
(iii) Lubricate each driveshaft fitting by following the Accomplishment Instructions, paragraph 3.B.(6), of Sikorsky 269 ASB B-299.1 for Model 269A, 269A-1, 269B, 269C, and TH-55A helicopters; 269C-1 ASB C1B-036.1 for Model 269C-1 helicopters; or 269D ASB DB-041.1 for Model 269D helicopters, each Revision 1 and dated February 24, 2012.
(2) Within 100 hours TIS after the inspections required by paragraph (e)(1) of this AD, and thereafter at intervals not exceeding 100 hours TIS:
(i) Remove the driveshaft from the gearbox and clean any grease from each end fitting.
(ii) Inspect the driveshaft for straightness, a twist, and a scratch. If the driveshaft has any bends, twists, or scratches, before further flight, replace the driveshaft.
(iii) Inspect the internal splines of each forward and aft fitting and each internal stop for wear. If there is any wear, before further flight, replace the fitting.
(iv) Inspect the drive splines of each splined drive fitting for wear. If there is any wear, before further flight, replace the splined drive fitting.
(v) Loosen the aft frame clamp and apply a torque of 750 to 1,000 inch-pounds to each main transmission aft pinion nut.
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.
