What happened
On 18 November 2003, an Embraer EMB-145EU, registration G-EMBL, was performing a scheduled passenger flight from Birmingham to Dusseldorf. During the takeoff roll, the aircraft required a more aggressive rotation than usual. As the aircraft accelerated, the flight crew and passengers noted significant vibrations and a loud, rhythmic banging noise emanating from beneath the aircraft.
As the landing gear retracted, the noise and vibration persisted, with passengers reporting a loud knocking sound in the rear of the cabin. The crew, observing no abnormal cockpit indications but noting the physical vibrations, elected to level off at 9,000 feet and requested an immediate return to Birmingham. The crew declared a PAN alert and prepared for an emergency landing.
Upon landing on Runway 33, the aircraft was met by the airfield fire service. While no fire was present, ground staff later discovered that the left inboard mainwheel tyre had shed its tread. The detached rubber had become trapped between the main gear and its side stay and had also struck the trailing edge of a flap, causing structural damage to the composite panel. There were no fatalities or injuries among the 43 passengers and 4 crew members.
The investigation
The AAIB investigation focused on the physical failure of the tyre and the condition of the wheel assembly. Examination of the number 2 tyre revealed that the tread had completely separated from the carcass. Investigators found large fractures in the tyre's inner liner and evidence of a localized breakdown within the casing plies. This failure allowed air to penetrate the carcass, pressurizing the area between the tread and the tyre body, which eventually forced the tread to lift and shed under rotational load.
Testing of the wheel assembly revealed that the thermal relief fuse plugs were leaking. Specifically, the investigation found that the bond between the eutectic material and the plug body had been compromised. While the exact cause of the initial leak was unclear, the investigation noted that the high-energy braking during the emergency landing had caused the remaining plugs to partially melt due to heat soak.
Findings
- The primary cause of the tyre failure was overstress in the tyre carcass, which was likely caused by the tyre operating in an under-inflated state.
- The loss of tyre pressure was attributed to leaks originating from the thermal relief fuse plugs.
- The tyre tread separation occurred during the takeoff rotation phase when the aircraft was heavily loaded.
- A lack of consistent tyre pressure recording in the technical logs meant the gradual loss of pressure went undetected.
- There was a breakdown in communication between wheel repairers and tyre re-treaders, as the reason for tyre removal (such as suspected under-inflation) was not being passed to the retreading facility.