David Learmount/LONDON

Emergency escape hatches on commercial aircraft used in Europe may have to be modified to make them easier and quicker to open, if the findings from a new UK study are implemented. This could lead to fleet retrofit requirements as well as new-build changes if the concepts are accepted by the European Joint Aviation Authorities (JAA).

The JAA has also just released an advance notice of proposed amendment (ANPA 25D-224) which would require considerably wider gangways alongside galley and lavatory units or cabin bulkheads close to main exits.

Both proposals result from a series of cabin-safety research studies commissioned by the UK Civil Aviation Authority following the 22 August 1985, accident to a British Air tours Boeing 737-200. Toxic fumes killed 55 people while they tried to escape from the aircraft, which had been set alight by an uncontained engine failure during the abandoned take-off run. A stewardess had to pull free escaping passengers who had jammed in the aisle between the galley bulkheads, the ANPA notes. The existing European and US minimum gangway width is 480mm. The proposed width is to be 720mm, but only for new-build aircraft.

The unpublished report on emergency escape hatches will be available "early in 1997", the CAA reveals. Existing "Type 3" escape hatches, fitted in most jet airliners and usually positioned above the wing, are considered to be potentially dangerous because, says the CAA, "-in some accidents, delays have occurred" as a result of the difficulties people have experienced in handling them. Each hatch weighs about 20kg, and has to be unlocked and manually ejected by the person - usually a passenger - seated next to it. This normally involves lifting and rotating the hatch so it can be thrown out of the exit aperture. Delay occurs while passengers struggle to do this.

Several systems to improve the hatch's ease of opening have been tested at Cranfield University in the UK. The CAA says that the system favoured at this stage is one which uses a spring-loaded mechanism and guide-rails which enable the hatch to be pulled inward, then easily pushed upwards to stow behind the overhead baggage lockers. An interim proposal in the report is that, if the hatch weighs more than 20kg, the weight must clearly be marked.

It is recommended that airlines allocate seats next to a Type 3 exit to people able to cope, and that they brief the individual concerned on how to operate it. In practice, this is often not done, the CAA admits.

Source: Flight International