Airworthiness Directive 98-24-21
one-timeAirworthiness Directives; Eurocopter France Model AS 332C, AS 332L, AS 332L1, and AS 332L2 Helicopters
What this AD requires
This amendment adopts a new airworthiness directive (AD) that is applicable to Eurocopter France (ECF) Model AS 332C, AS 332L, AS 332L1, and AS 332L2 helicopters. This action requires inserting instructions into the Model AS 332C, AS 332L, AS 332L1, and AS 332L2 Rotorcraft Flight Manuals (RFMs) regarding actions to take if either the ``OVSP 1'' or ``OVSP 2'' amber warning light illuminates. This action also requires, for the Model AS 332C, AS 332L, and AS 332L1 helicopters, measuring the vibration levels of the engine-to-main gearbox (MGB) shaft, inspecting the torque on the MGB coupling bolts, and conducting an engine-to-MGB coupling 23,000 revolutions per minute (RPM) input check. This amendment is prompted by an accident involving a Model AS 332L1 helicopter in which the helicopter experienced an engine overspeed resulting in failure of both engines. The actions specified in this AD are intended to prevent failure of the rotor drive engine-to-MGB coupling, which, if undetected, could result in an engine overspeed leading to an uncontained engine turbine wheel burst and subsequent loss of control of the helicopter.
Which aircraft AD 98-24-21 applies to
Engine-to-main gearbox (MGB) coupling on the 23,000 RPM input shafts; flight manual warning-light procedure for all four variants, plus periodic vibration/torque checks for AS332C/L/L1 (torque spec depends on whether Eurocopter France MOD 0752316 tie-bolt replacement is incorporated).
Whether AD 98-24-21 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.