AD 97-24-17
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Bell Helicopter Textron Canada Limited | 407 | Airworthiness Directives; Bell Helicopter Textron Canada Model 407 Helicopters |
Unsafe Condition
Cracks, fretting, corrosion, or improper torque in the tail rotor drive coupling disc pack; insufficient lubrication of hanger bearings causing cage and ball separation; undertorqued tail rotor gearbox attachment nuts leading to loss of clamping force and torque loss due to corrosion inhibitive adhesive barrier tape.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Visually inspect disc pack couplings for scratches, cracks, fretting, corrosion, and proper torque; lubricate oil cooler blower shaft hanger bearings and check for binding; inspect splines on oil cooler blower shaft and splined flywheel adapter; remove corrosion inhibitive adhesive barrier tape between tail rotor gearbox and support assembly; inspect gearbox, support assembly, mounting pads for wear, cracks, elongated holes; inspect gearbox attachment nuts for proper torquing; inspect tailboom skin for corrosion or damaged rivets.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Effective April 16, 1998, with priority letter AD 97-24-17 issued November 20, 1997, requiring immediate compliance for known U.S. owners/operators. Others must comply by this amendment's effective date.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Bell Helicopter Textron Canada Model 407 helicopters, all serial numbers except those starting from serial number 53225 which have the design change eliminating barrier tape.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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