Lebanese investigators have disclosed that a Boeing 767-300ER converted freighter sustained serious fuselage buckling during a hard landing at Beirut, during which its nose-wheel twice heavily struck the runway.

The DHL Aviation aircraft – arriving from Bahrain with three crew members on 18 September – conducted a stable approach to runway 16, down to a height of 20ft, according to preliminary findings from the Lebanese ministry of transport’s investigation commission.

Flight-data recorder information indicates its rate of descent at that point was 650ft/min, and that the main landing-gear touched down with an impact of 1.35g.

But when the nose-gear made runway contact, about 1.5s later, its impact was higher at 1.77g.

The recorder then indicates that the nose-wheel momentarily lifted off before striking the runway at over 1.9g, while the elevators experienced rapid changes in deflection, between 11.1° in one direction and 20.6° in the other.

Upper fuselage buckling DHL 767 2-c-Lebanese ministry of transport

Source: Lebanese ministry of transport

Wrinkling of the fuselage discovered after the 767 freighter landed hard in Beirut

According to the first officer, who was flying, the aircraft “pitched up violently” and the speed of events was such that he could not immediately regain control of the yoke. The first officer had over 3,140h on type.

The captain testified to the inquiry commission that the aircraft “lurched up” before the nose dropped, the nose-gear hitting the runway with such force that his headset and spectacles were thrown from his head.

In a DHL flightcrew air safety report accompanying the inquiry findings, the pilots mention that the auto-speedbrake was inoperative and the speedbrakes were extended manually during the landing.

None of the crew members – two pilots and an engineer – was injured.

But the aircraft’s fuselage was badly wrinkled forward of the wing and aft of the cargo door, at around station 64. The buckling occurred on both the left and right sides of the fuselage and across its crown.

Upper fuselage buckling DHL 767-c-Lebanese ministry of transport

Source: Lebanese ministry of transport

Buckling damage extended to both sides of the fuselage and the crown

The jet (A9C-DHAB), powered by General Electric CF6 engines, was originally delivered as a passenger aircraft to American Airlines in 1999 and underwent conversion as a BDSF freighter – a designation indicating a Bedek Aviation Group modification.

As a result of the accident the aircraft was grounded.

No cockpit-voice recorder information is available, because the circuit-breaker was not immediately pulled.

The inquiry says it has requested calculations from Boeing which would determine the maximum load on the nose-wheel during the event.

It has not reached any final conclusions on the circumstances.

One of United Airlines’ Boeing 767-300ERs experienced a similar occurrence on 29 July this year, when its nose-wheel bounced on the runway, after a stable approach and normal main-gear touchdown, during a landing at Houston.

The initial nose-gear impact of 1.4g prompted the first officer, the flying pilot, to pull on the yoke in an attempt to prevent a second hard contact, but the nose-gear struck the runway at 1.6g.

This resulted in substantial wrinkling of the upper fuselage just forward of the twinjet’s engines.