Airworthiness Directive 97-10-15
one-timeAirworthiness Directives; Sikorsky Aircraft-Manufactured Model S- 64F Helicopters
What this AD requires
This amendment adopts a new airworthiness directive (AD), applicable to Sikorsky Aircraft-manufactured Model S-64F helicopters, that requires inspections, and replacement, if necessary, of the main gearbox second stage lower planetary plate (plate). This amendment is prompted by two incidents in which the plate was found cracked. The actions specified by this AD are intended to prevent failure of the plate due to fatigue cracking, which could lead to failure of the main gearbox and subsequent loss of control of the helicopter.
Which aircraft AD 97-10-15 applies to
Applies to main gearbox assemblies containing second-stage lower planetary plate P/N 6435-20516-101 with 2,000+ hrs TIS: daily main oil filter inspection for magnesium contamination, repetitive 500-hr TIS inspection/replacement per Erickson SB 64F35-2A, and rework at next overhaul. Helicopter model not stated in extracted text (SB number 64F35-2A suggests Erickson S-64 series, not confirmed).
Whether AD 97-10-15 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.