Airworthiness Directive · Amendment 39-11235 · Sikorsky Aircraft-Manufactured Model CH-54B Helicopters
Sikorsky Aircraft-Manufactured Model CH-54B Helicopters
CH-54B helicopters with main gearbox second stage lower planetary plate (plate), part number (P/N) 6435-20516-101, installed, certificated in any category.
This amendment adopts a new airworthiness directive (AD), applicable to Sikorsky Aircraft-manufactured Model CH-54B helicopters, that requires initial and recurring inspections and rework or replacement, if necessary, of the second stage lower planetary plate (plate). This amendment is prompted by two reports of cracked plates that have been found during overhaul and inspections. The actions specified by this AD are intended to prevent failure of the main gearbox plate due to fatigue cracking, which could lead to failure of the main gearbox and subsequent loss of control of the helicopter.
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.
