Airworthiness Directive · Amendment 39-9833 · Air Tractor, Inc. Models AT-250, AT- 300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT- 502 Airplanes
Air Tractor, Inc. Models AT-250, AT- 300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT- 502 Airplanes
The following airplane models and serial numbers, certificated in any category, that are equipped with a Gerdes part number (P/N) A-850-5 or Cleveland P/N 60-9 parking brake valve : Model Serial Numbers AT-250.............................. 250-0491. AT-300.............................. 300-0001 through 300-0708. AT-301.............................. 301-0001 through 301-0708. AT-302.............................. 302-0001 through 302-0708. AT-400.............................. 400-0001 through 400-0708. AT-400A............................. 400A-0001 through 400A-0708. AT-401.............................. 401-0001 through 401-0708. AT-402.............................. 402-0001 through 402-0708. AT-501.............................. 501-0001 through 501-0036. AT-502.............................. 502-0001 through 502-0036.
This amendment adopts a new airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT-250, AT- 300, AT-301, AT-302, AT-400, AT-400A, AT-401, AT-402, AT-501, and AT- 502 airplanes that are equipped with a Gerdes part number (P/N) A-850-5 or Cleveland P/N 60-9 parking brake valve. This action requires replacing the parking brake valve with a Scott P/N 4500A-2 parking brake valve. This AD results from several reports of the parking brake valve inadvertently slipping to the ``PARK'' position during flight, which causes constant pressure on the brakes. When the pilot applies the brake upon landing, this pressure causes the airplane to overturn. The actions specified by this AD are intended to prevent the airplane from overturning because of extreme pressure applied to the brake if the parking brake valve inadvertently slips to the ``PARK'' position during flight.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
