CAA to await tests on new 747 'pins': British airlines will be told to replace part blamed for crashes once substitute gains approval in US

THE Civil Aviation Authority will order British Airways and Virgin to change suspect parts on their Boeing 747 aircraft as soon as its US counterpart gives the go-ahead.

As revealed exclusively in the Independent, Boeing is rushing the development of a new fuse pin, the part connecting the engine to the wing which is designed to break in a crash or if heavy vibration is threatening the structure of the wing.

The premature failure of the fuse pins on the inner starboard engine is suspected to have caused two crashes involving 747 freighters resulting, in both cases, in two engines falling off: in Amsterdam last year when an El Al aircraft crashed into a block of flats killing an estimated 50 people, and in Taiwan in December 1991 when five crew died.

The US Federal Aviation Administration said yesterday that it would make the fitting of the new fuse pin mandatory as soon as tests could be successfully completed, but this could take several weeks after the design of the pin is completed. Boeing does not expect to produce the new pins until 'the early to mid-summer'. A spokeswoman for the CAA said that it would immediately follow any instruction from the FAA.

Boeing is satisfied that the shorter periods between inspections issued by aviation authorities after the Taiwan crash will ensure there is no repeat of the failures until the pins on all the world's 900 747s can be replaced. Nevertheless, Boeing is so worried that it recently resumed its search in the South China Sea for the lost fuse pins from the China Airlines aircraft.

The only two UK airlines which operate 747s, British Airways and Virgin, both replaced all their fuse pins - each aircraft has 16 - last autumn, after the Amsterdam crash. Boeing report that about a fifth of all fuse pins replaced after the directive had traces of corrosion.

The new pins, made of stainless rather than high carbon steel, are being developed following computer programmes on stress levels showed stresses '8 or 10' times higher than expected on parts of the pins.