Freightdoors & Fuselage flexing

[Jhieminga]

A while back the subject of main-deck cargo doors came up in the History&Nostalgia forum, and especially the problems you can get with getting them closed due to flexing of the fuselage.

Reichman posted this about the VC10:
A great deal of care still has to taken when using the freight door on the VC10. If the door is opened while the nosewheel isn't straight, or if the aircraft is on slightly uneven ground, there will be trouble closing the door. Methods I've seen employed in the past to close it have been:

a) 10 people stood on each wingtip jumping up and down.

b) A catering truck parked up against the door with as many people as possible pushing against the door.

c) A combination of a and b.

d) Start the aircraft up, taxi around the apron and try again.

Still the Queen of the Skies though.

I started thinking and decided to post this question here:
Is this still a problem that plagues aircraft with main-deck cargo doors or are more modern fuselages less susceptible to flexing due to loading and/or moving?

Anybody with interesting stories/theories?

[Compass Call]

We used to have problems closing the cabin freight door of the BAC 1-11. Usually only if it had been left open for any length of time or if somebody had done a fuel uplift while the door was open. The door lock latches would not engage. The only answer was to keep on trying and hope they would engage or start the engine and use the engine driven pump for the extra pressure. I know the BAC 1-11 is not modern but it is the same vintage as the VC 10! :)

[Volume]

Not only the same vintage, also the same state of design :D

(It´s not broken, it´s british)

[AfgAirOps]

Jhieminga,

I've come across this problem on the B707 & the DC-10 (the latter being a lot less susceptible). It was usually caused by being parked on a slightly uneven surface, especially if the aircraft was stopped during a tight turn.

On the B707 the solution was usually to tow or taxi it to a more level area & on the DC-10 (where the problem was usually opening not closing) it was usually to tow the aircraft very slowly whilst trying the door.

Main-deck cargo door vent-door switches were often a problem on the '10 & the first place people would check if there was a problem with the door.

Cheers

[QAVION]

The fuselage design is not exactly modern, but leaving cabin doors R & L3 open on a 747-400 during refuelling may mean that you can't close them afterwards.

If towing the aircraft around doesn't fix it, you may have to defuel the aircraft.

Regards.
Q.

[Elliot Moose]

We used to have problems getting the big (9') cargo door to close on the HS-748 if there was too much weight in the rear section. It wasn't as much of a problem with the original factory built pressurized aircraft, but it still happened. I flew some modified unpressurized "big door" hawkers that were always a pain to close with a load on, but that was due to insufficient strengthening during the mod. :rolleyes:

[galaxy flyer]

Just a useless story... but the Galaxy has huge doors. The visor is probably 80-90 linear feet. And we only occaisionally have trouble latching them. The problem is not fuselage flexing, so much as, all the electric targets that indicate closed. It's sort of like the old Christmas tree lights where any one bulb out took the whole string out. If there is a strong wind blowing, it requires some thought about which door to close first, front or back.

[Lu Zuckerman]

Story 1: The AH1J helicopter had a maintenance access panel on the right side in the cockpit area. It was a structural panel, which was retained (if memory serves me right) by 72 screws. If you removed the panel in the field first of all it would be difficult because of some of the screws binding and being rendered useless because of the binding. Once you got the panel off you could not get the screw holes to lign up. The helicopter had to be completely unloaded dynamically which meant that it had to be on jacks and in a hanger away from the wind. It was difficult to do this when operating in the field so a lot of maintenance was deferred.

Story 2: I worked for a firm that did cargo conversions. They worked on the cheap so instead of using aircraft manufacture supplied parts in the conversion they would contract them out to backyard mechanics. Some of the cargo door actuators had very complex kinematics which were not reflected in the cheaper parts so, when the doors were opened or closed there was serious binding which really ran up the maintenance charges. They also modified a US Navy DC-9 Nightingale into a combi. When the aircraft went into service the pilots said that when on autopilot the aircraft was like a porpoise. They traced the problem to the fact that the modification firm did not tie the new reinforced cargo deck into the fuselage, which allowed the fuselage to flex to a very high level.

:D