Airworthiness Directive 97-25-09
one-timeAirworthiness Directives; Allison Engine Company Model 250-C40B Turboshaft Engines
What this AD requires
This amendment adopts a new airworthiness directive (AD) that is applicable to Allison Engine Company Model 250-C40B turboshaft engines. This action requires installation of a placard requiring pilots to record torque level and time in service operating above 86% engine torque until the defective parts have been replaced, no later than December 31, 2000, or when certain maintenance actions are accomplished, or when certain operational restrictions are exceeded, whichever occurs earliest. This amendment is prompted by a report from Allison Engine Company of a manufacturing defect in certain helical power takeoff gearshaft assemblies, identified by serial numbers. The actions specified in this AD are intended to prevent fatigue failure of the helical power takeoff gearshaft assembly, which could result in a loss of engine power and inflight engine shutdown.
Which aircraft AD 97-25-09 applies to
Applies to engines, gearboxes, and gears identified by serial number in Allison Alert Commercial Engine Bulletin (CEB) No. A-72-5009, dated May 21, 1997. Installed on and limited to the twin-engine Bell Helicopter Textron 430 series helicopters.
Whether AD 97-25-09 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.