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-   -   Your opinion on an old controversial accident (https://www.pprune.org/safety-crm-qa-emergency-response-planning/372186-your-opinion-old-controversial-accident.html)

JammedStab 30th Apr 2009 22:07

Your opinion on an old controversial accident
 
I have recently read the accident report and petition for reconsideration concerning a TWA 727 that nearly crashed in 1979.

From the internet " while the plane was cruising at 39,000 feet, its #7 slat extended, initiating a sharp roll to the right. The roll continued despite the corrective measures taken by the autopilot and the human pilot. The aircraft went into a spiral dive, losing about 34,000 feet in 63 seconds. Control was regained at about 8,000 feet, by the decision of the Captain to extend the landing gear in an attempt to slow the aircraft, and following the #7 slat being torn off from the aircraft and symmetry of lift being re-established."

"The NTSB investigated the incident and established after eliminating all individual and combined sources of mechanical failure, that the extension of the slats was due to the flight crew manipulating the flap/slat controls in an inappropriate manner. The crew suggested instead that an actuator on the #7 slat had failed, causing its inadvertent deployment"

ALPA filed a petition for reconsideration in 1983 claiming the same as the crew. The NTSB dismissed this petition. ALPA claimed in a second and very detailed petition that a rudder hardover was the cause which the NTSB also dismissed.

All of which leaves me wondering if anyone out there has some thoughts on this whole incident.

http://en.wikipedia.org/wiki/TWA_Flight_841_(1979)

NeilMaybin 30th Apr 2009 22:51

No Wikipedia Entry? Try Aviation Safety Network
 
ASN Aircraft accident Boeing 727-31 N840TW Saginaw, MI

MikeNYC 30th Apr 2009 23:25

Wikipedia entry exists... trailing ")" on URL was left off by original poster.

Link: TWA Flight 841 (1979) - Wikipedia, the free encyclopedia

Bealzebub 1st May 2009 02:09


The aircraft had a cockpit voice recorder (CVR) and it was undamaged. 21 minutes of the 30 minute tape were blank. The remaining 9 minutes of the tape had good fidelity but pertained only to the flightcrew conversations after the aircraft was on the ground at Detroit. Tests showed no discrepancies in the CVR’s electrical and recording systems. The CVR can be bulk erased from the flightdeck after the aircraft was on the ground with its parking brake engaged, but the Captain stated that he usually activates the Bulk Erase feature at the conclusion of each flight but he could not recall having done so this time. The rest of the flight crew stated that they did not erase the tape nor did they see the captain activate the erase button on the CVR control panel.

:rolleyes:

JammedStab 1st May 2009 02:29

ALPA claimed the possibility of a faulty CVR and that the NTSB should have investigated the recorder more thoroughly.

Bealzebub 1st May 2009 02:56


but the Captain stated that he usually activates the Bulk Erase feature at the conclusion of each flight but he could not recall having done so this time.
With so much adrenelin coursing through this crew, it is perhaps noteworthy that the Captain did not recall whether he had or had not followed his usual practice of erasing the flight recorder ?

Having narrowly survived such a potentially catastophic event, erasing one of the two primary sources of recorded evidence (the FDR couldn't be erased,) would be such a strange course of action, that you might reasonably think the Captain would remember either taking this course of action or not?

ALPA of course were present to advocate the position of one of their members.

john_tullamarine 1st May 2009 03:10

the Captain stated that he usually activates the Bulk Erase feature at the conclusion of each flight

One needs to keep in mind that the underlying philosophy, if somewhat eroded by cases such at the Dash-8 in NZ etc., was that the CVR should only be used in cases where the crew were not available for the investigation (ie dead).

It was routine in Oz to bulk erase on chocks following all flights.

That's not to say that it might well have assisted the crew's situation at the enquiry had they chosen not to erase the CVR ?

parabellum 1st May 2009 13:46

Have I missed something? The reports seem to skate round what I was told actually happened.

On the B727, when at altitude, like FL390, is was not uncommon to pull the CB for the leading edge devices and then select Flap 1 with the lever, (which operated both slats and flaps), as Flap 1 did not change the camber of the wing, the flap went straight out and only increased the surface area thus giving a bit more lift and improving the Vs1.2 margin. Very non standard but OK if it worked. In the case of the TWA incident the wrong CB was pulled, the trailing edge flaps were inhibited and the slats started to deploy when the lever was moved to Flaps 1 causing the aircraft to go temporarily out of control.

If that has already been clearly stated somewhere and I have missed it, I apologise and will delete.

JammedStab 1st May 2009 17:21

The first possible selection for flaps on the 727 is 2°. Are you aware of people actually performing this manouver on the 727 or any other aircraft through more than just long handed down rumours?

According to the NTSB, the flaps were intentionally selected to and did extend to 2°. The appropriate LED's extended as well for whatever reason, perhaps the wrong CB being pulled as you stated. The when the flaps were retracted, the #7 slat remained extended due to a pre-existing misalignment of that slat due to a failed bolt.

parabellum 2nd May 2009 01:33

Sorry, my error, I should have said Flap 2,

Yes I do know 727 crew who regularly extended the trailing edge having first inhibited the leading edge devices.

The TWA crew would probably have got away with it if the #7 slat wasn't broken.

JammedStab 3rd May 2009 04:18


Originally Posted by IGh (Post 4901052)

During deposition, "Dean" Kampshore (IIC) admitted that NTSB never found any airline pilot that had ever attempted the Boeing Scenario.

Was there much likelyhood of someone actually admitting to doing or attempting to do this sort of thing if they actually had tried?

parabellum 3rd May 2009 05:00

Well I'm obviously not going to name names or airlines here am I? Whether they were telling the truth or not I have no idea but it seems strange that three senior B727 captains would make up the same story, they are all retired now and I doubt if they will be posting here either!

I have only repeated what I was told first hand, hardly gossip!

JammedStab 3rd May 2009 13:10


Originally Posted by IGh (Post 4901052)
The CVR tape seemed odd -- nothing. The Bulk Erase feature had been activated. But which sort of fault led to such an activation of that mishap-CVR's Bulk Erase field over the magnetic tape? Most pilots couldn't tell you difference between the Power Change-over tone, versus the Bulk Erase field, on Lockheed A-100 Voice Recorder.

It certainly was quite the coincidence to have a rudder hardover(as claimed by petitioners) and a CVR bulk erase failure at almost exactly the same time on the same flight with a faulty slat retract mechanism.

BelArgUSA 3rd May 2009 23:09

Flying too high...
 
Back when I started airline flying, 1969, the big "concern" was "high altitude stall".
I recall captains taking airplanes well above a safe flight level.
As an example, overflying towering CBs in the USA Midwest...
I recall being at FL410 in a B-720 where chart maximum was FL370/380.
This captain "ace" got us 2 or 3 times in a stick shaker... Was about Mach .82.
xxx
As a flight engineer and first officer (727) some captains extended T/E flaps disabling leading edge devices.
The VFE speed limit on 727 (and 747) is directly related to leading edge VFE structural limit.
The "T/E Flaps 1 position" (747) or "T/E Flaps 2 position" (727) is not a VFE speed limit.
For these position, the trailing edge flaps extend the surface of the wing, not any drag increase.
But the VFE related to these positions is related to L/E flaps structure.
It is a certification limit. Maximum altitude for flaps 707-727-747 = 20,000 ft.
xxx
With the DC8-60/70 - there was a VFE and MFE limit.
Flaps 12 was 230 KIAS VFE or .46 Mach. OK to extend above FL 200.
Stall recovery procedure DC8...? Extend first notch of flaps, any level. Approved UAL procedure.
xxx
So - try to figure what "Hoot" Gibson did... I suspect he did...
Just was not an approved procedure. Never has been, but some did...
He probably wanted to be higher to avoid CAT, than flying 100 NM off his track...
xxx
The bulk erase...? Yes - in the "old days" I always did use that feature...
The last 15 years of my career, I no longer used that feature.
Every pilots bust at least "one limitation" (or regulation) per flight.
You never do...? - Shall I call you a liar...?
And now retired, I could not care less...
xxx
:*
Happy contrails

JammedStab 4th May 2009 02:04


Originally Posted by IGh (Post 4901052)

During deposition, "Dean" Kampshore (IIC) admitted that NTSB never found any airline pilot that had ever attempted the Boeing Scenario. Perhaps you can provide documentation that was never provided by Boeing nor the NTSB re' specific pilot use of the Boeing Scenario.

Based on the above post, it looks like it took minimal effort on my part to provide documentation.

"As a flight engineer and first officer (727) some captains extended T/E flaps disabling leading edge devices."

JammedStab 5th May 2009 02:53

Not my area of expertise. I am only looking for, as the thread title suggests, opinions of others. However, I am quite glad to see that I was able to end a longstanding argument and add to the investigations failure to find a crewmember who had performed this flap operation manouver in cruise flight. It obviously is something that was done at the time.

JammedStab 6th May 2009 13:17

I don't think the fact of military background or not has anything to do with whetther or not they would try something like this. Plenty of example in the civilian and military of crews doing things they shouldn't.

Flight tests did find according to the NTSB, when the so-called Boeing manouver was conducted, a similar FDR trace to the upset aircraft.

BelArgUSA 8th May 2009 13:48

Recalling this old incident - forgot to mention another concern then often discussed.
Those of you familiar with 707-727-747, recall the outboard ailerons.
As soon as the outboard T/E flaps extend, the outboard ailerons are operating.
And you are familiar with the flex of the outer half of the wing... i.e. 727.
xxx
While everyone is preoccupied about the L/E panel extending, what happened with outboard ailerons.
Would it be possible that these outboard ailerons caused flight control reversal...
It is the reason Boeing locks the outboard ailerons for high altitude/high speed.
Could explain the complete loss of control of the aircraft... full roll, was it...?
xxx
:eek:
Happy contrails

JammedStab 12th May 2009 02:46


Originally Posted by BelArgUSA (Post 4913976)
As soon as the outboard T/E flaps extend, the outboard ailerons are operating.
And you are familiar with the flex of the outer half of the wing... i.e. 727.

Would it be possible that these outboard ailerons caused flight control reversal...
It is the reason Boeing locks the outboard ailerons for high altitude/high speed.
Could explain the complete loss of control of the aircraft... full roll, was it...?
xxx
:eek:
Happy contrails

Can't say for sure but at flaps 2°, while outboard ailerons are not locked any more, they are only partially available. Not sure how much but on a 200 series at 5° the big book says 80% outboard aileron deflection capability. So somewhat and perhaps significantly less is available at 2° flap.

2 rolls I believe.

KOLDO 27th Feb 2015 12:53

B727 Flaps / Slats, my two cents.
 
Dear aviators,
The famous C/B is labelled as LE bypass valve. Just one scenario when it comes into play, like alternate flap use. First touch on the up/down swithc, will extend all LE, then will move the flap motor and by the torque tubes, will move the jackscrews attached to the wing rear spar, and so and so…
The LE slats will remain extended, then the speed limit of 230 kt. because this.
If we have normal hydraulics, we can retract again the LE flaps, using the above mentioned and famous C/B, after closing the red guarded switch to activate the alternate extension system, so now all fluid has access to LE lines an these can be retracted again.
Said that, each LE actuator has a locking device, initially electric, bult in each individual actuator. To unlock we need hyd. pressure in.
My opinion is that the mentioned idea of extending trailing edge flaps alone, was NOT an operating approved procedure at any airline as far as I know.
Inadvertent deployment???? for me it is very remote, however needs more study.

Thanks


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