Being of an inquisitive nature and like many on this thread, I wondered what the real reason for the flaps /20,000' limitation on the L-1011 was for. At the end of a re-currency session, with some minutes to spare, I asked the sim instructor if we could try flaps above 20,000.
Both of us were surprised in the change in roll response, and the massive PIO oscillations that ensued. The experiment was terminated.
Whether the sim was true to the aircraft characteristics I do not know.
411A, Glhcarl, and FEHoppy will be much more familiar with the mixers for spoilers/flaps/ ailerons than me, but I have a feeling that the laws may not be valid(or flight proven) for above FL200.

Huck:

Well; funnily enough, I did a six-month contract (on leave of absence) with Air Pacific (Fiji). The aeroplane (N821L) was an ex- Air New Zealand KSSU Dash-30.

My F/O was on furlough from Western and lived in MSP. He ended up with NW and is still there after all these years in his new Delta uniform.

I used to see him a lot when he was in the left seat of the DC-10 with NW when he came to LGW and he used to flatter me terribly in the pub over lunch about what I had managed to teach him that the US Navy had somehow missed!

PS: Did you ever come across a KSSU DC-10? Believe it or not, they even managed to put the hinges on the flightdeck door on the wrong side which could be mildly embarrassing when exiting the forward lav and trying to get back into the office!

BarbiesBoyFriend

I believe the reason most transport aircraft have the FL200 flap extension limitation has more to do with design load limits. I believe when you get above FL200 the severe turbulence certification load limits are greater and therefore would require quite a big jump in structural strength to meet those standards.

So most manufacturers limit flap extension to FL200 to keep from needing to certify them to greater loads. I would be quite surprised to learn the DC10/MD10 or MD11 do not have the 20K limitation.

And JW411 you should read the attached article before debunking the facts. They were in the flight levels and the FO suggested extending the slats. I don't see how your stories have anything to do with the subject. :rolleyes:

Small world, JW411. I was the guy they brought in to give a day's training on the AINS-70 to the Air Pacific crews.

I'm glad to see the ones who know the DC-10 best are praising it.

GB

Squawk 7700

Without in any way demeaning you post above.

Does turbulence know about this FL200 restriction?

Graybeard:

Well, well; I remember that day. You taught us well and your story about finding the carbon discs from the AINS-70 on the ice cap from the ANZ crash was particularly fascinating. Thank you.

I operated the ANZ KSSU (strip engine instruments) -30s when BA had 1.8 on lease from ANZ.

3 months, all expenses paid, in Auckland as a 30 year old single.

We used to do the sim with KLM in Amsterdam - 4 "wonderfully liquid" days twice a year.

To return to the alternate gear extension limit.

I think, I may be wrong, it was lower as the doors didn't close after lowering the gear by the alternate method.

I also remember that BA had a -30, after BA took over BCAL (ATLAS?, round instruments), which had an autoslat extension on climb out of LGW around F/L 150.

I think the crew got distracted but I can't remember the FMA mode they were in.

This scenario was part of the next sim check.

Alt extension speed is 230.

Alt retraction doesn't exist, but it's a funny question to ask people when you're bored.

It has nothing to do with what happens in the real world, only what the certification standards are. I'm just trying to explain where that FL200 restriction comes from, I'm not claiming it is accurate to the real world.

Just like evacuation certification requires manufacturers to get everyone out in 90 seconds. That doesn't mean that 90 seconds after a crash the aircraft will explode, it is just a certification benchmark that is used.

I'm talking certification here, plain and simple. It doesn't mean that deploying slats or flaps above FL200 will kill you, I am just puzled as to why they would do that before pushing the nose down to reatach the airflow. If, after carrying out the proper stall recovery procedure you still find yourself dropping like a stone, then by all means, do whatever you need to do to get that wing flying again.

FWIW, that limit was a factor in a 727 holding hitting a mountain in south Colombia.

"My father was in the initial cadre at Northwest on the DC-10 as a young flight engineer, must have been about 1970."


Huckster,

May have flown with your father either on the '10 or 727 after '85.

Springer

Boeing has the 20,000 ft. limit on all the models I have flown. I have heard (though not seen it in writing) it is due to the flaps not being tested above this altitude. Its quite understandable since when would you want to use flaps anywhere near this height. McDonnell/Douglas/Boeing doesn't have any altitude limits on the 717 flap/slat altitude. The slats do drop the stall speed significantly and is part of the stall recovery procedures if within airspeed/mach limits.

It is interesting, is it not, that the DC-10 has flap and slat limits promulgated in Mach number, as well as IAS, considering several posts by those in the know that they haven't seen any 20K limitation on the -10. :8

There is no certification requirement to test flaps or slats above FL200, which is why it is not done.


Some manufacturers then only publish an IAS and FL200 limitation. Others publish IAS and Mach limitations without the FL200 limit.


I think, were you to look, you will find that the Mach limits correspond to the IAS limit at FL200. Those publishing only IAS limits probably do so in an attempt to simplify things with fewer numbers to memorize.

Well, like most aircraft it had some very good points and once the kinks had been ironed out it was a very well-loved machine for it's day - unfortunately it had it's growing pains played out in public.

Let's not kid ourselves, the AOM was written in blood.

It is now a very reliable and safe machine, though.

The FL200 limitation on flaps is because of the airflow/airspeed on the top surface of the wing.

It is close to the critical Mach number and/or even exceeding Mcrit when flaps are extended above FL200.

Update
 

I am more concerned with the Cargo. Did it make it to its destination ontime, or was there a delay ?

Interesting reading:

http://www.ntsb.gov/dockets/aviation...075/409278.pdf

There was some info posted regarding the outboard ailerons and trim rates on the DC-10 that are incorrect.

Inboard slat retraction locks out the outboard ailerons on the DC-10 and are unlocked by

AGE IS 15

1. Alternate Gear Extension
2. Inboard Slats
3. Flaps greater than 15.

The slats can be extended on the -30 at 270 IAS or .55 mach and the outboard ailerons are active. There is no 250 speed switch for the outboard ailerons, especially since CMS at high gross weights could be 280+ and you want the added maneuverability the outboard ailerons provide.

The inboard slats unlock the outboard ailerons so not to aggravate a stall which deploys the outboard slats only on an auto-slat extension.

The slat settings are 13.7 degrees for Auto, 15 for T/O and 19 for LDG.

Stab rate goes to 1/2 rate above 25,000 ft. This is why using the alternate stab trim switches is a better way to trim the plane for passenger or box comfort until reaching 25,000 ft. Otherwise the whole plane bucks in the back with each thumbswitch click.

The 10 is a great machine! Especially if you know how to fly it!:D

Cheers