WARNING LIGHTS CAN LIE.

By Brian Spurway.Airframes.


On 31st of March 1974 British European Airways (BEA) and British Overseas Airways Corporation (BOAC) were both dissolved and British Airways (BA) was formed; just before this happened BEA employees had been on strike, the reason for which is not material here.

On the 4th of that month a Turkish Airlines Douglas DC10 landed at Paris Orly en-route from Istanbul to Heathrow, it was carrying just 167 passengers (11 of whom disembarked at Orly); a small number of pre-booked passengers embarked but there were still many empty seats left for the onward flight. Stuck in Paris that day were hundreds of British passengers, stranded there because of the BEA strike, and many of them were able to grab those available seats; the total number of British passengers then on board the aircraft amounted to 176 out of the total number of 346. There were also 11 crew members - what followed was, at that time, the World's worst ever aircraft accident with the loss of all on board.

Climbing out of Paris and passing through about 9000 feet, having been cleared to continue climbing to 23000 feet, an outward opening aft cargo door burst open; the floor between the hitherto pressurised cargo hold and the passenger cabin was unable to stand the sudden pressure differential so it catastrophically collapsed allowing two triple seat rows of passengers to be sucked down and out through the opening. Hydraulic lines, and the rear fin-mounted No 2 Engine controls, all running beneath the passenger floor were severed. The engine shut down, the hydraulically operated flying controls became useless and the aircraft immediately started an uncontrollable dive that ended with a catastrophic crash in the Ermenonville Forest. Bad design, bad practise and inexperience had led to the aircraft getting airborne with the cargo door in an unsafe condition and, as soon as sufficient pressure differential between the inside of the pressurised hold and the outside atmosphere reached a certain level, the door burst open.

I may be wrong but I can't remember a Pressurisation phase for us 'riggers' at Halton, its importance as a subject never occurred to me when on Hunters at Chivenor and was totally irrelevant during my time as both 'rigger' and flight engineer on Hastings. However my eyes widened considerably when I joined the Hercules fleet and found that understanding all about pressurisation would be good idea - and not understanding it could be very dangerous. Not exact, but as an example, assuming the outward opening cargo ramp at the back of the Hercules measures approximately 10 feet by 15 feet, or 21600 square inches, flying at a level requiring the maximum pressure differential of about 7½ lbs per square inch then something over 80 tonnes would be doing its bloody best to open it; let alone the forces acting on the 23 panes of glass that make the Hercules flight deck so light and airy! No wonder that manufacturers of large pressurised aircraft like to fit 'plug' type inward opening doors where possible but, as in the case of the Hercules' ramp and the DC10's (and most other airliners') cargo doors, maximising space inside necessitated the doors being outward opening.

I had the pleasure, over a five year period, of being a flight engineer on the Lockheed Tristar, reckoned by many an aficionado to be a better designed aeroplane than the DC10; it also had outward opening cargo doors but, unlike the DC10, it did have provision for the rapid (immediate?) equalisation of pressure between the hold and the passenger cabin should a cargo door open in flight - I really wouldn't want to be the one to test this out, but I very nearly was!

Most of the flying I did during the last three years up to my retirement in 1994 was short-haul charter but there were long-haul charters too and they always had the benefit of longer stay-overs, sometimes this amounted to as long as seven days. Very much a 'one-off' for me was a trip to Los Angeles in the summer of 1992 - arriving on 27th June and due to leave on 7th July (Thanksgiving Day in LA, well that was an experience!). Our departure that day was to be late in the evening; I seem to recall we were to be the last departure from LAX before it closed for the night. A cabin packed with families, noisy, cheerful, some probably a bit too cheerful, but "Hey come on!" they're on their way home after having had a great experience - mostly at Disney I guess. The APU was running, we were ready to start engines just waiting for one 'red' light to go out on my FEWP (Flight Engineer's Warning Panel - an acronym I may just have made up as I don't remember the real one!) - and that just happened to be the larger of the two starboard aft cargo doors!!

The guy handling us outside, on intercom, assured us that the door was closed and that the 'green' light on the door itself was illuminated indicating that the locks had engaged. The door was opened and re-closed but that darned 'red' light on my panel was adamant, it was going to stay glowing even though the 'green' one on the door came on again and we were re-assured that the door was closed. Out with the 'Go No-go' list - it confirmed that it would be OK to go with my 'red' light on so long as the door was positively checked 'closed', i.e. locks fully engaged. A couple more cycles of the door produced no change; tension in the cabin started to rise as passengers became aware of the hold up and sensed that there was a problem 'up front'. We were on a remote parking area, no air-bridge, so steps had to be recovered and brought up to the aircraft so that I could go and examine the recalcitrant door. Sure enough the 'green' light was shining brightly in the gathering gloom and the two dark-skinned gentlemen standing there looking at it (lloaders, engineers, or whatever) were positive that all was OK - their opinion was that the door had to be correctly locked because the 'green' light said it was. They agreed to try a manual opening and closing using a cranking system -all new stuff to me -but nothing made any difference. Then, with the door opened, one of them jumped into the hold, took a pair of 'Mole Grips' out of his pocket and said he was going to "adjust the proximity-switch" (sort microswitch, I guessed - again all new stuff to me) but there was no way I'd agree to him doing that. Words were exchanged and the two dark-skinned gentlemen departed the scene in a serious 'Huff' - with words somewhat like "It's your f*****g problem!" Leaving the door open I climbed back up to the flight deck and found I had to force my way through some agitated and angry passengers who were doing their best to get through the flight deck door so as to badger the Captain - one loudly threatening legal action against him because of the delay and his missing an important business meeting.

It got much worse because LAX now decided enough was enough and were about to close shop - we were given a deadline "Go before midnight or else!"

I had a few tools secreted in my flight bag so I beat a hasty retreat back to the now very peaceful cargo door. I really had no idea what to do but, in desperation, climbed into the hold and started to pull some of the sound-proofing off the inside of the door - 'Eureka', I found the problem straight away. The door had been closing OK but the electric actuator that should have powered the locks into position was never going to fulfil its function; its attachment bracket had broken away from the door's structure leaving that end of it hanging free. The locks had never fully engaged, probably didn't even move towards the locked position at all, but the actuator had worked OK and its internal limit-switch had recorded its full and correct linear movement by bringing on the 'green' light each time we cycled the door. My 'red' light was telling the truth after all - the door may have looked closed but it sure as hell wasn't locked there! Had we got airborne the door would have opened at some stage, probably just under the influence of the slipstream rather than hanging on until a pressure differential caused it to do so and, because of its proximity to the starboard tail plane, would undoubtedly have caused severe damage and, quite likely, some degree of control loss.

I now had the long-lasting pleasure, before the coaches arrived to take us all to hotels for another night in LA, of being able to confront the arrogant potential 'litigant', get him out of the flight deck where he was still haranguing the Captain, and hand him the actuator and its broken bracket - a few words to him about the DC10 crash in France and the slightly exaggerated suggestion that it could easily have happened to us somewhat altered his attitude and helped to open his wallet later that evening in the hotel bar - not a common occurrence for us to stay at the same hotel as some of our passengers but it worked out well as his wallet wasn't the only one that opened that night/morning.

The aeroplane was fixed and the next evening after a full 24 hour delay we flew to Bangor in Maine where a waiting crew took over to take the passengers on to Gatwick - things, with just the crew in the hotel at Bangor, were much quieter for the shorter than planned stop-over waiting for a Company charter from Orlando that we had been rostered to take home.