AD 2021-04-06 Describes The Unsafe Condition As A Missing Release Bar Retaining Screw On A Harley-Type Buckle Assembly

The FAA is adopting a new airworthiness directive (AD) for all Pilatus Aircraft Ltd. (Pilatus) Model PC-7 airplanes.

This AD results from mandatory continuing airworthiness information (MCAI) issued by the aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as a missing release bar retaining screw on a Harley-type buckle assembly installed on a harness shoulder strap. This condition, if not corrected, could lead to loss of pilot restraint and consequently loss of airplane control or injuries to the crew. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective February 12, 2021.

Supplementary Information: The Federal Office of Civil Aviation (FOCA), which is the aviation authority for Switzerland, has issued FOCA AD HB-2021-001-E, dated January 8, 2021 (referred to after this as “the MCAI”), to address the unsafe condition on Pilatus Model PC-7 airplanes.

The MCAI states:

• An occurrence was reported where in an in service event a missing release bar retaining screw on a Harley-type buckle assembly installed on a harness shoulder strap on an ejection seat was detected.
• This condition, if not corrected, could lead to loss of pilot restraint and consequently loss of aeroplane control or injuries to the crew.
• To address this potential unsafe condition, Pilatus and IrvinGQ issued the [service bulletins] SBs to provide inspection instructions.
• For the reason described above, this [FOCA] AD requires the inspection of the Harley-type buckle assemblies on the seat harnesses of the front and rear seats, as defined in this AD, and prohibits (re-) installation of affected parts.

FOCA advises that the release bar retaining screws on the affected Harley-type buckle assemblies were incorrectly peened during manufacture. This inadequate peening of the retaining screws has led to loose screws that can potentially be removed by hand or the actual screw falling out of the assemblies. You may examine the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-0049.

FMI: www.regulations.gov