A thin sheet stainless steel shroud surrounding the jet pipe of a locally-based North American Aviation F-86A Sabre jet fighter needed specialist attention from TWI. The purpose of the shroud is to deflect any leaking exhaust gases away from the internal structure during the brief period, between start-up, and the engine reaching running temperature, when previously weeping seals around the jet expand and become leakproof.
Although within limits, several small cracks and tears were in need of attention during the Sabre's annual maintenance if the aircraft was to achieve its Permit to Fly. Because there is no direct civilian equivalent, historic ex-military aircraft fly under this rigorous permit system rather than the Civil Aviation Authority's certificate of airworthiness.
Using TIG welding, and an appropriate consumable for the aged material, TWI was able to arrest and repair cracks in the wafer thin material. The cracked state of the shroud has been attributed to strain and thermally related fatigue. During its 64 year life the component would have endured many thousands of heating and cooling cycles.
The Sabre is best known for its service in the Korean War where it was pitted against the Soviet MiG-15.
The Golden Apple Trust, which owns the Sabre, believe it to be the oldest airworthy jet-powered aircraft in the world: its first flight was in March 1949. Aircraft of this vintage used largely aluminium at manufacture but some titanium is known to have been used. The adoption of titanium was in its infancy in the late forties. As the first swept-wing fighter aircraft the F-86 was a completely new breed of aircraft: in terms of performance and technology it was in an entirely different class to any that had gone before. The Sabre's structure had to withstand not only the rigors of high-speed flight, but also extreme temperatures, especially in local areas surrounding the engine turbine and jet pipe.
For further information read about TWI Services to the Aerospace
industry or contact us