Summary
We propose to adopt a new airworthiness directive (AD) for certain Honeywell International Inc. TPE331-5, -5A, -5AB, -5B, -10, - 10R, -10U, -10UF, -10UG, -10UGR, and -10UR model turboprop engines. This proposed AD was prompted by engine propeller shaft coupling failures, leading to unexpected propeller pitch changes resulting in high aerodynamic and asymmetric drag on the airplanes using these engines. This proposed AD would require removing certain part number (P/N) propeller shaft couplings from service. This proposed AD would also require inserting a copy of Honeywell International Inc. Operating Information Letter OI331-26, dated March 2, 2010, into the applicable Airplane Flight Manuals. We are proposing this AD to prevent loss of airplane control, leading to an accident.