747-200 door handle movement in flight

[Dave Martin]

Something that happened to me many years ago (almost a decade now) - thought any "experts" here might be able to shed some light on it.

Travelling as a dependent on staff travel over the pacific resulted in me being seated in the fold down cabin crew seat at the very rear of the aircraft (747-200) right next to the door furtherest aft, left side. Hit some of the most intense turbulence I have ever had the missfortune of experiencing. Bins opening, crap flying everywhere, screaming pax, sick bags being filled and spilled left right and center.

This continued for a good 15 minutes or so and was a very intense experience. At some stage through this a loud, hollow, BANG came from the area of the door next to me. I looked across, it was still there and really couldn't see anything out of the ordinary. Some 5 minutes or so later, I think when the turb had abated somewhat, a cabin attendent staggered down the isle, looked at the door, eyes widened and she proceeded to push the door-handle-bar down about another 30 degrees.

I had at that point soloed and held enough flying hours to have experienced "unusual aircraft attitudes" - hence, while alarmed I was certainly not about to grab anything I shouldn't. Hosty did ask me if I had touched it the door, to which I said "no". Doubt was pretty well etched across her face though and I can only assume I was probably held to be the culprit.

Anyone know what the sequence of events was here? Is this prone to happen in strong turb? Was it potentially dangerous or indicative of damage to the aircraft? Rode to the Honolulu hotel with the crew who said it was the worst they had ever experienced (and that we were lucky it was night time, otherwise the flexing wings and swinging engines would have caused heart attacks)

As I understand the door won't blow obviosuly because the cabin pressure prevents it from being opened, but the handle movement is a concern.

Cheers,
Dave

[mooney59]

Dave, you writing a novel?

[Manc]

Handle movement of this magnitude is not unknown. When the handle is in the fully closed position, the mechanism is rigged so that it is in an overcentre position and some force is required to pull the handle up. I suppose if the mechanism was near the lower end of it's tolerance combined with the turbulence, the effects of which would be worst at the rear of the aircraft, the vibration could overcome the force required to move the mechanism.

The door handle is connected to the door hinge but the first stage of handle movement does not affect the hinge but disengages the latches. The limited force that the handle can apply to the hinge is such that even very small differential pressures prevent the door from opening - the initial step change in cabin pressure as the pressurisation kicks in on the climb out is probably sufficient. So as long as the cabin is pressurised, the door is held shut and further handle movement is not likely. Consequently, the door latches are only required to properly locate the door in the frame as it's closed and keep it closed while the aircraft is unpressurised ie during taxi and takeoff so there's not really a flight safety issue here.

There is a related AAIB Bulletin (http://www.dft.gov.uk/stellent/groups/dft_avsafety/documents/page/dft_avsafety_501725.hcsp) that goes into more detail.

[Dave Martin]

Thanks for the answer and web link. I was pretty much aware there wasn't any danger of the door opening, but really wanted some re-assurance it wasn't unusual for the handle to move in such a way.

I've had this nagging feeling over the years that the crew must have pictured me with as a terrified passenger from take-off to landing with a death grip on the door handle!

Interesting the section on clearing smoke from the cabin. I remember reading this as a kid from my fathers ops manuals. It always seemed to conflict with the concept of doors not being able to be opened in flight

Cheers,
Dave

P.S. Mooney, judging by my spelling mistakes, do you think I would be capable of it?

[126.9]

What's really scary Dave is that if you didn't touch it, someone on the outside must have..?

:}

[Dave Martin]

Yeah, that was my real concern...just didn't want to say it in as many words. :D

[PAXboy]

"someone on the outside must have..?"

Probably a stowaway who wanted to get in and use the toilet. :yuk:

[Techman]

Nahh, it's that little gremlin that eats away at your pylons...;)

[SLFguy]

"Two cabin crew were instructed to keep pressure applied to the handle. The flight engineer became concerned not only for the integrity of the door, but also about possible implications for the pressurisation of the aircraft. He therefore called the engineers at Gatwick and discussed the problem with them. They suggested letting go of the handle to see where it would stop. The flight crew declined to do this"............. hehe