AD NUMBER: 2009-07-05
MANUFACTURER: ATR
SUBJECT: Airworthiness Directive 2009-07-05
SUMMARY: We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAIdescribes the unsafe condition as: Incomplete accomplishment instructions in SB [service bulletin] ATR 72-27-1059 original issue and Revision 1, failed to mention installation of cotter pins to secure he self locking nuts after re-installation of the modified Pitch Uncoupling Mechanism (PUM), when connecting the elevator control linkage rods to the PUM input levers and the PUM output rods to the elevator bellcranks (on both sides). Because of the non-installation of these four cotter pins, the fail-safe criteria of the design requirements on the pitch control are no longer met. Such a failure could cause the loss of one self locking nut and would result in the loss of pitch control on one side-Captain or First Officer-or the loss of control of one elevator surface.The symmetrical loss of two concerned self-locking nuts could lead to a complete loss of the pitchcontrol. * * * * * We are issuing this AD to require actions to correct the unsafe condition on these products.

FMI: www.faa.gov/regulations_policies/airworthiness_directives/