The crew of an aircraft waiting for clearance to taxi across an active runway observed a departing Boeing 767-300 scrape its hydraulic tail bumper during rotation. This information was then relayed to the pilot in command of the departing aircraft who elected to continue the flight in accordance with the non-normal checklist. Maintenance personnel inspected the aircraft when it arrived in Sydney and determined the strike was minor. A repaint of the skid was all that was required for the aircraft to continue in service.
A second officer undergoing promotional training to first officer was the handling pilot during the incident. This was the fourth sector of line training and the takeoff was conducted during a moderately gusty 15 kt wind. The crosswind component was estimated to be in the order of 8-13 kts. Takeoff and initial climb performance depend on rotating at the correct airspeed and proper rate, to the rotation target attitude. Early, rapid or over-rotation may cause aft fuselage contact with the runway. Aft fuselage contact will occur at a pitch attitude of 9.8 degrees on the 767-300 with the wheels on the runway and landing gear oleos extended. For optimum takeoff and initial climb performance, a smooth continuous rotation is initiated at the calculated rotation speed (VR) to the rotation target attitude. Rotation should be smooth and at an average pitch rate of 2 to 3 degrees per second. A 10 degree body attitude will be achieved in approximately 3 to 5 seconds with all engines operating, and liftoff will occur at a pitch attitude of 8 to 9 degrees. When the rotation rate is greater than 3 degrees per second, the minimum tail clearance decreases, and may result in contact with the ground. The minimum tail skid clearance on a normal takeoff is approximately 61 cm and occurs after liftoff. This is a consequence of the aircraft geometry and the dynamic forces that are acting after rotation has been initiated.
Analysis of Quick Access Recorder (QAR) data for this incident indicated that rotation commenced at an airspeed approximately 5 kts above the calculated VR. The recorded data also showed the pitch attitude of the aircraft during liftoff did not exceed the attitude that would result in aft fuselage contact. However, the aircraft was subject to a rapid rotation during much of the liftoff period. A maximum pitch rate of 4.6 degrees per second occurred one quarter of a second after main landing gear liftoff, coinciding with minimum tail clearance.
Boeing data (Airliner, Jul-Sep 1994) suggests the most common factors in takeoff tail strike events are excessive rotation rate and early rotation. In this particular incident, ground contact was slight, resulting in removal of paint from the tail skid. The tail skid performed its intended function, that is, providing a contact barrier which protects the aft fuselage against takeoff tail strikes. It is considered that the inexperience of the handling pilot and the gusty crosswind conditions contributed to the tail strike incident
The crew viewed the QAR data for reference and were debriefed by the operator's Flight Safety Department. Details of the incident were promulgated to other crew and the operator indicated the Flight Safety Department is actively monitoring the situation in regard to tail strikes.
|Date:||21 July 2000||Investigation status:||Completed|
|Time:||0736 hours EST|
|State:||Victoria||Occurrence type:||Ground strike|
|Release date:||01 August 2000||Occurrence category:||Incident|
|Report status:||Final||Highest injury level:||None|
|Aircraft manufacturer||The Boeing Company|
|Type of operation||Air Transport High Capacity|
|Damage to aircraft||Nil|
|Departure point||Melbourne, VIC|
|Departure time||0738 hours EST|