What happened
On 15 June 2003, a Boeing 73 and 436, registration G-DOCL, departed London Gatwick Airport on a scheduled passenger flight. Shortly after takeoff, the flight crew was notified by the operator that debris had been discovered on the runway. Subsequent identification confirmed that the debris had originated from the aircraft itself. While the crew reported no unusual noises during the initial climb, the aircraft was required to return to Gatwick.
Because the aircraft was above its maximum landing weight, the crew declared a PAN and entered a holding pattern at FL240. To manage braking energy, the crew followed the Quick Reference Handbook to reduce the aircraft's weight to below 53,000 kg by burning off fuel. The landing was performed using flap 40 configuration, manual speedbrakes, and maximum reverse thrust. Upon landing, the aircraft's right main landing gear fly door and right wing trailing edge sustained damage, and a main landing gear tyre was destroyed. There were no fatalities or injuries among the 6 crew members or 117 passengers.
The investigation
Investigators examined the aircraft and recovered numerous pieces of tyre tread and a section of the landing gear fly door from the runway. The operator found that the outboard right main landing gear tyre had remained inflated despite the loss of tread.
Technical analysis of the tyre revealed it had undergone five retread processes. The investigation focused on the interface between the original carcass and the retreaded material. While the retread layer itself remained intact, the tread had separated from the carcass at the original manufactured interface. Detailed examination of the recovered fragments showed no evidence of under-inflation or external cuts, but did reveal severe heat damage and discoloration around the circumference of the tread.
Findings
- The tyre had undergone five retread cycles and had completed 297 landings since its most recent retread.
- The separation occurred at the original manufactured carcass-to-tread interface.
- Severe heat damage was present on both the tread and the carcass.
- A previously identified minor aberration in the tyre, noted during the fifth retread, was located in the area where the separation eventually occurred.
- The cause of the separation could not be definitively established, but it was attributed to either a manufacturing flaw within the original sub-tread/casing interface or progressive internal heat build-up caused by extreme operational conditions.