Lufthansa 737 Pressurisation Problem

[John Boeman]

Accident: Lufthansa B735 near Leipzig on Oct 19th 2010, cabin pressure problems injure 5
By Simon Hradecky, created Tuesday, Oct 19th 2010 16:03Z, last updated Tuesday, Oct 19th 2010 16:03Z

The Aviation Herald (http://www.avherald.com:)

A Lufthansa Boeing 737-500, registration D-ABIR performing flight LH-1104 from Frankfurt/Main to Leipzig (Germany) with 70 passengers and 5 crew, was enroute at FL230 when cabin pressure problems occurred, the oxygen masks were not released. The crew requested priority for the approach and landing in Leipzig and landed safely 36 minutes after departure from Frankfurt. 5 passengers needed to be taken to hospitals with circulatory problems and ear pain.

Lufthansa said, there had been cabin pressure irregularities during the flight, the passenger oxygen masks were not released. 5 passengers were taken to hospitals for treatment of circulatory problems and ear pain. The cause of the irregularity is not yet known.

[captplaystation]

Leaky old birds, with a capricious cabin pressure controller to boot, the classics. Always surprised to see Luftie , or indeed any "legacy" carrier, still operating them.
They are getting on a bit , and the pressurisation system was hardly glitchproof when new, 20 years later, as I am finding out again, it is pretty naf :hmm:

[Denti]

It is believed that the boeing fleet will be replaced by the Bombardier C-Series.

By the way, classic does not necessarily mean old and bad pressurization controllers, ours (300 and 500s) all had the same digital pressurization system we now have in the NG.

[captplaystation]

True indeed, but in spite of this they seem to play up a bit more, and of course they are working hard to contain the effects of a leaky old airframe too.

[RockShock]

Ok then, sorry to put my 0.02$ as an SLF between, but what can one do if such situation happens on the flight? Is there some remedy that can be applied by a PAX when no masks are available? Breath deeply, stop breathing at all, etc? :} I understand that the masks alone don't help for the pain in the ears, but in general, what could be done? And just out of my interest, why isn't there a manual release button for the masks to drop out?

Cheers
RS

[BOAC]

A bit of a guess here, RS, but it may be that the crew noticed a problem with the cabin pressure and made an emergency descent (which can cause an element of distress and sometimes ear problems). In doing so they may well have kept the cabin pressure sufficiently high so as not to require oxygen mask deployment? There is indeed a manual mask deployment facility in the cockpit. In short I suspect that there was in fact no need for the masks.

[8314]

Okay, if they were in FL230, than they will get down pretty quick. Up to FL250 there is no need for a Pax drop down system at all.
Our Q400 for example flies 25000 without...:ok:

[notfred]

If the masks don't drop it's going to be because there is no need for supplemental oxygen. The only thing remaining is dealing with the sudden pressure changes on the body.

I'm SLF but from my scuba diving training you want to keep breathing to keep the pressure in your lungs equal to that on your body - holding your breath can damage your lungs when scuba diving and whilst aircraft have less pressure range I assume the same things will apply. Just try clearing the ears normally remembering that you will have an initial decrease and then an increase in pressure.

[mccdatabase]

of course they are working hard to contain the effects of a leaky old airframe too.


Cobblers !!

The Classic aircraft are subject to leak rate checks as laid down in the AMM on a fairly regular basis, they are no worse (or better) than the NG variant,

[BOAC]

Your cobblers and I raise you twaddle. I used to fly a 300 that was incapable of pressurising from take-off single pack 'cos it leaked so much. Theory and practice, eh?

[Cough]

I flew a -400 back from BOD which didn't pressurise on a single pack.

Once they changed the old gummed up fwd outflow valve it did...

[mccdatabase]

I used to fly a 300 that was incapable of pressurising from take-off single pack 'cos it leaked so much

See your twaddle and raise you a balderdash !

One badly maintained aircraft does not mean that the type is in someway deficient, we have an ageing 300 fleet any of which that can happily operate on one pack if the necessity arises albeit at a reduced altitude of FL250.,

I call that putting the theory into practice.

[skadi]

holding your breath can damage your lungs

But only during ascend, not in a descent!

skadi

[arearadar]

I`ll make a point of not flying with you then.

Dave

[TheWanderer]

Quote:
holding your breath can damage your lungs
But only during ascend, not in a descent!

skadi

Loss of pressurization is a rapid ascend inside the previous pressurized cabin.

[TheWanderer]

FRA - LEJ is about 150NM great circle distance, so they were not cruising at a high level.

@RockShock:

Breath normally and stay calm, keep your seat belt fastened at all times when on your seat.

If masks do not drop, there is no need for masks.
Masks drop automatically at about 14.000 ft cabin altitude or at any time when manually deployed by the pilot. The pilot has a manual deploy switch in the cockpit.
When deployed, masks need to be activated by the passenger by pulling them down to you.
Once activated, oxygen will be produced from a chemical reaction and mixed with normal cabin air while breathing through your mask.

The chemical reaction produces heat and there might be a burning or electrical smell that origins from the chemical reaction and is normal.

There is one oxygen generator supplying oxygen to all masks for one row of seats.

Oxygen supply is available for about 20 minutes and cannot be stopped once it is activated due to the nature of the chemical reaction.

[sooperdede]

Can't exaplaine better than this..

[RockShock]

Most informative TheWanderer, thanks! My only concern was that the pasengers of the flight were taken to the hospital with ear pains etc, but indeed this things couldn't be prevented with the oxygen masks and were simply the result of the depressurization of the environment they were in. This still makes me wonder, though, what to do in case the pressure drops fast to make the pressures equal in your body with the surrounding pressure - as I understand the oxygen mask is only a remedy to allow me breath with an air mixture that contains more oxygen than available at high attitudes and keep me conscious. However, the body itself is still exposed to rapid pressure change and the question here is what to do to relieve some of the damage the pressure change can cause... Probably the post of notfred is also a good suggestion.

Cheers,
RS

[onboard]

Oxygen supply is available for about 20 minutes and cannot be stopped once it is activated due to the nature of the chemical reaction.

True for the aircraft in question. For those that didn't know, there are also systems where the flow of oxygen to individual masks CAN be shut off.

[demomonkey]

I have a professional and personal interest in 737 pressurisation problems having had my own encounter several years ago. Luckily no injuries followed and to be fair the pax had little idea what the nature of the problem was, only that we were diverting.

I'm uncertain as to why 5 pax would be injured. As the rubber jungle didn't drop we know that the cabin altitude did not exceed 14,000'. The problem with the QRH drill is that if you only have a slow decompression (statistically much more likely) the a/c will overpressurise in the descent. If there is then a sudden release of pressure (overpressure valve releasing or crew manually depressurising the airframe when below 10,000') injuries could occur. Anyway, well done to the crew for getting it safely back on the ground and not thinking it was the T/O Config warning!

DM

[heavy.airbourne]

Most probably the crew had to switch to manual control of cabin pressure as the auto-control had failed, which almost always results in some major pressure bumps. This should hurt people with blocked Eustachian tubes, up to burst eardrums, and might disorientate the vestibular system, resulting in airsickness, sometimes. Nothing serious, though.