On March 8, 2017, about 1452 eastern standard time, Ameristar Air Cargo, Inc., dba Ameristar Charters, flight 9363, a Boeing MD-83 airplane, N786TW, overran the departure end of runway 23L at Willow Run Airport (YIP), Ypsilanti, Michigan, after the captain executed a rejected takeoff. The 110 passengers and 6 flight crewmembers evacuated the airplane via emergency escape slides; however, one slide failed to inflate and could not be used. One passenger received a minor injury, and the airplane sustained substantial damage. The airplane was operated under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121 as an on-demand charter flight and was destined for Washington Dulles International Airport, Dulles, Virginia. Visual flight rules conditions prevailed at YIP at the time of the accident.
During the takeoff roll, the captain, who was the pilot flying, executed the rejected takeoff 12 seconds after the airplane achieved V1 (takeoff decision speed) because he perceived that the airplane did not respond normally when he pulled back on the control column to command rotation. (V1 is defined, in part, as the maximum speed in the takeoff by which a rejected takeoff must be initiated to ensure that a safe stop can be completed within the remaining runway.) The check airman, who was the pilot monitoring (and was providing airplane differences training to the captain), questioned the captain’s decision to reject the takeoff after V1 but adhered to company standard operating procedures and did not attempt to intervene.
Data from the airplane’s flight data recorder (FDR) showed that the airplane’s right elevator was positioned full trailing edge down (TED) when the flight crew first powered up the airplane on the day of the accident and remained there throughout the accident sequence. An airplane performance study (based, in part, on FDR data) confirmed that the airplane did not respond in pitch when the captain pulled on the control column. Based on the study’s comparison with a previous takeoff, the National Transportation Safety Board (NTSB) determined that the airplane’s lack of rotational response to the control column input did not become apparent to the captain in time for him to have stopped the airplane on the runway.
Before the accident flight, the airplane had been parked on the ramp at YIP for 2 days near a large hangar, and the elevators (which, by design, did not have gust locks) were exposed to high, gusting surface wind conditions. Postaccident examination showed that the right elevator’s geared tab’s inboard actuating crank and links had moved beyond their normal range of travel and became locked overcenter, effectively jamming the right elevator in a full-TED position and rendering the airplane incapable of rotation during takeoff. The speed of the surface wind and gusts at YIP did not exceed the certification design limit or maintenance inspection criteria for the airplane. However, the NTSB determined the airflow at the airplane’s parked location was affected by the presence of the large hangar that generated localized turbulence with a vertical component that moved the elevator surfaces rapidly up and down, which resulted in impacts against the elevator mechanical stops, imposing dynamic loads sufficient to jam the right elevator.
The probable cause of this accident was the jammed condition of the airplane’s right elevator, which resulted from exposure to localized, dynamic wind while the airplane was parked and rendered the airplane unable to rotate during takeoff. Contributing to the accident were (1) the effect of a large structure on the gusting surface wind at the airplane’s parked location, which led to turbulent gust loads on the right elevator sufficient to jam it, even though the horizontal surface wind speed was below the certification design limit and maintenance inspection criteria for the airplane, and (2) the lack of a means to enable the flight crew to detect a jammed elevator during preflight checks for the Boeing MD-83 airplane. Contributing to the survivability of the accident was the captain’s timely and appropriate decision to reject the takeoff, the check airman’s disciplined adherence to standard operating procedures after the captain called for the rejected takeoff, and the dimensionally compliant runway safety area where the overrun occurred.
Safety issues identified in this report include:
- the lack of a means to enable flight crews of Boeing DC-9/MD-80 series and 717 model airplanes to verify before takeoff that the elevators are not jammed,
- the need for improved in-service inspection techniques for critical rotating parts of all engines,
- the need for lower ground gust criteria for elevator physical inspections and operational checks by maintenance personnel for Boeing DC 9/MD-80 series and 717 model airplanes,
- the potential inadequacy of ground gust limit loads for the certification of transport-category airplanes,
- the lack of procedures for operators of Boeing DC-9/MD-80 series and 717 model airplanes to monitor the wind that
affects parked airplanes,
- the lack of procedures for weather observers related to sign off and backup augmentation responsibilities during a facility evacuation, and
- evacuation slide malfunction.
As a result of this investigation, the NTSB makes safety recommendations to the FAA and The Boeing Company and reclassifies two previously issued safety recommendations to the FAA.