ANC05IA002 · Boeing MD-11F

The airline transport certificated flight crew was preparing to depart on a 14 CFR Part 91 ferry flight in an MD-11F freighter airplane with one of its three engines, the tail-mounted center engine inoperative, and the fuselage center landing gear (CLG) retracted. When the crew applied thrust for takeoff, the airplane pitched up, and the bottom of the tail struck the runway. The takeoff was aborted, and inspection disclosed minor damage to the lower empennage. In a letter to the NTSB investigator-in-charge, and in further discussions, company management stated that the crew had calculated the airplane's weight and balance based upon data for the CLG extended. They noted that they were unaware at the time of the incident flight that the airplane's aft limit of center of gravity (CG) moved significantly forward with the CLG retracted. They reported that the crew's CG calculations were reviewed by support, flight management, and dispatch staff prior to the flight. They also noted that while the crew was trained in two-engine ferry operations, their training did not include information regarding the CG shift with the CLG retracted. The operator said that while the appropriate weight and balance information was provided in an appendix to the approved Boeing Aircraft Flight Manual (AFM), the Boeing MD-11 Two-Engine Ferry Operations Manual the crew was using did not reference any change in the CG with the CLG retracted. The ferry manual also recommends in the pretakeoff checklist that the CLG be retracted. A review of the weight and balance data provided by the operator disclosed that the airplane was slightly aft of the zero fuel weight (ZFW) allowable center of gravity limit even when the calculations were computed using the more liberal CLG extended CG limits. When they were computed using the correct, CLG retracted data, the airplane's ZFW CG was approximately 3.2 per cent of mean aerodynamic chord (MAC) aft of the allowable limit. Discussions with Boeing staff disclosed that the MD-11 Two-Engine Ferry Manual was taken from the DC-10's. The DC-10 is a predecessor to the MD-11, and is similar in appearance and configuration, although the DC-10's fuselage is several feet shorter. The DC-10, however, does not have a forward shift in the aft CG limit when the CLG is retracted. Boeing personnel noted that although the MD-11's ferry manual recommends that the CLG be retracted for a two-engine ferry, they state that it is not essential. Boeing has issued a Flight Operations Bulletin (FOB), dated November 14, 2005, to MD-11 and DC-10 operators indicating that all DC-10 and MD-11 Two-Engine Ferry Manuals are out of date, and they cannot vouch for their accuracy. The FOB also has information on how the operators may obtain additional, current two-engine ferry performance/procedures information.

Verbatim NTSB analysis and probable cause from the NTSB dataset