Worn Tail Rotor Pitch Link Spherical Bearings Could Cause Pitch Link Failure

The FAA has issued an Emergency AD (EAD) for Bell Helicopter Textron Canada Limited (Bell) Model 429 helicopters.

The EAD was prompted by several reports of worn tail rotor pitch link spherical bearings. This condition, if not corrected, could result in pitch link failure and subsequent loss of control of the helicopter.

Transport Canada, which is the aviation authority for Canada, has issued EAD No. CF-2015-16, dated July 2, 2015, to correct an unsafe condition for the Bell Model 429 helicopters. Transport Canada advises that in-service reports showed that the tail rotor pitch link spherical bearings have experienced early and accelerated wear. On three occasions, bearings were found worn beyond limits during pre-flight inspections, showing a radial and axial play that was easily detectable. In one case, the spherical bearing separated from the tail rotor pitch link, resulting in damage to the tail rotor blade pitch horn assembly. In another case, the spherical bearing had been inspected and found acceptable during a maintenance inspection; about “1 hour air time” later, it was found worn beyond limits during a pre-flight inspection.

This helicopter has been approved by the aviation authority of Canada and is approved for operation in the United States. Pursuant to our bilateral agreement with Canada, Transport Canada, its technical representative, has notified us of the unsafe condition described in its EAD. We are issuing this EAD because we evaluated all information provided by Transport Canada and determined the unsafe condition exists and is likely to exist or develop on other helicopters of the same type design.

Bell has issued Alert Service Bulletin 429-15-16, dated February 18, 2015 (ASB). The ASB applies to Bell Model 429 helicopters, S/N 57001 and subsequent, which have accumulated more than 50 hours. The ASB specifies the following actions:

• Inspecting both inboard and outboard tail rotor pitch link assemblies for axial and radial play;
• If abnormal wear or bearing play is detected, removing the affected tail rotor pitch link and performing a dimensional check of both axial and radial play; and
• Replacing any tail rotor pitch link assembly 429-012-112-101 or -103 or pitch link bearing 429-312-107-103 that exceeds the allowable limits.

This EAD requires, before further flight, and thereafter at intervals not to exceed 50 hours time-in-service (TIS), inspecting each inboard and outboard tail rotor pitch link assembly for axial or radial bearing play. If there is axial or radial bearing play, removing the tail rotor pitch link and performing a dimensional inspection for wear are required. If there is wear that exceeds the allowable limits, replacing the tail rotor pitch link assembly is required.

The FAA says the EAD is an interim action. If final action is later identified, further rulemaking may be considered.

(Image from file)

FMI: EAD