AD NUMBER: AD 2009-26-05

MANUFACTURER: PILATUS Aircraft Ltd. Model PC-7 Airplanes
SUBJECT: Airworthiness Directive AD 2009-26-05

SUMMARY: We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

This Airworthiness Directive (AD) is prompted due to the discovery of cracks caused by stress corrosion in the main-gear support struts. All the main-gear support struts that had cracks were made from material AA2024-T351 which has a lower resistance to stress corrosion cracking.

Such cracks, if undetected, could lead to the failure of the strut during landing which could then cause the Main Landing Gear (MLG) to collapse.

We are issuing this AD to require actions to correct the unsafe condition on these products.

DATES: This AD becomes effective February 1, 2010. On February 1, 2010, the Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD.

FMI: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/list/2009-26-05?OpenDocument