AD 2018-02-13 Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

This AD supersedes AD 2017-07-02, Amendment 39-18840 (82 FR 15120, March 27, 2017).

(1) Before further flight: (i) For Model 269D helicopters, remove from service any KAflex engine side drive shaft P/N SKCP2738-7 and any KAflex pulley side drive shaft P/N SKCP2738-5 that has 6,000 or more hours time-in-service (TIS). Thereafter, remove from service any KAflex engine side drive shaft P/N SKCP2738-7 and any KAflex pulley side drive shaft P/N SKCP2738-5 before accumulating 6,000 hours TIS. (ii) For Model 269D Configuration A helicopters, remove from service any KAflex engine side drive shaft P/N SKCP2738-7 and any KAflex pulley side drive shaft P/N SKCP2738-5 that has 1,200 or more hours TIS. Thereafter, remove from service any KAflex engine side drive shaft P/N SKCP2738-7 and any KAflex pulley side drive shaft P/N SKCP2738-5 before accumulating 1,200 hours TIS. (iii) If interchanged between Model 269D and Model 269D Configuration A helicopters, remove from service any KAflex engine side drive shaft P/N SKCP2738-7 and any KAflex pulley side drive shaft P/N SKCP2738-5 that has 1,200 or more hours TIS. Thereafter, if interchanged between Model 269D and Model 269D Configuration A helicopters, remove from service any KAflex engine side drive shaft P/N SKCP2738-7 and any KAflex pulley side drive shaft P/N SKCP2738-5 before accumulating 1,200 hours TIS. (2) Within 25 hours TIS, and thereafter at intervals not to exceed 25 hours TIS, using a belt drive alignment tool 269T3303-003, inspect the lower pulley to engine alignment by engaging the tool on the drive shaft and inserting in the lower pulley bore. Rotate the tool 360° around the drive shaft and inspect for interference. If there is any interference with the rotation of the tool, before further flight, adjust the engine elevation alignment to eliminate the interference. (3) Within 25 hours TIS, and thereafter at intervals not to exceed 100 hours TIS: (i) Remove the drive shaft to adapter bolt and inspect the drive shaft alignment. Engage and disengage the splines a minimum of 3 times by sliding the engine power output shaft in and out of the engine. Inspect the alignment at each 90° interval by rotating the lower pulley with the power shaft disengaged. Determine whether the adapter slides on and off the drive shaft splines without spline engagement interference or resistance along the entire length of movement. If there is any spline engagement interference or resistance, before further flight, replace both the engine side and pulley side drive shafts. (ii) Inspect each drive shaft for a crack, any corrosion or pitting, a nick, a dent, and a scratch. If there is a crack, any corrosion or pitting, a nick, a dent, or a scratch that exceeds allowable limits, before further flight, replace both the engine side and pulley side drive shafts. (4) Within 25 hours TIS, and thereafter at intervals not to exceed 400 hours TIS, remove the engine side drive shaft and pulley side drive shaft and perform the following: (i) Inspect each flex frame (frame) bolted joint (joint) for movement by hand. If there is any movement, before further flight, replace both the engine side and pulley side drive shafts. (ii) Visually inspect each joint for fretting corrosion (which might be indicated by metallic particles) and each frame and mount bolt torque stripe for movement. If there is any fretting corrosion or torque stripe movement, before further flight, replace both the engine side and pulley side drive shafts. (iii) Using a 10x or higher power magnifying glass, visually inspect each joint for fretting and for a crack around the bolt head and washer side, and around the nut and washer side. Also inspect both sides of each frame for a crack on the inside and outside corner radii and radii edge (four). If there is any fretting, a crack at any point over the full circumference (360°) of the bolt head and washer side or the nut and washer side, or a crack in any of the corner radii edges, before further flight, replace both the engine side and pulley side drive shafts. (5) As an optional terminating action to the repetitive inspections in this AD, you may install KAflex engine side drive shaft P/N SKCP2738-9 and KAflex pulley side drive shaft P/N SKCP2738-101.

(1) The Manager, Boston ACO Branch, FAA, may approve AMOCs for this AD. Send your proposal to: Michael Schwetz, Aviation Safety Engineer, Boston ACO Branch, Compliance and Airworthiness Division, FAA, 1200 District Avenue, Burlington, Massachusetts 01803; telephone (781) 238-7761; email michael.schwetz@faa.gov. (2) For operations conducted under a 14 CFR part 119 operating certificate or under 14 CFR part 91, subpart K, we suggest that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office, before operating any aircraft complying with this AD through an AMOC.

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.

This AD defines the unsafe condition as failure of a drive shaft. This condition could result in loss of rotor drive and subsequent loss of control of the helicopter.