Easyjet B737 pitch-down incident 12 January

[Muaskid]

Anyone know any more about this from the NTSB website - sounds pretty serious. NTSB Identification: DCA09WA023
Scheduled 14 CFR Non-U.S., Commercial operation of easyJet
Incident occurred Monday, January 12, 2009 in East Anglia, United Kingdom
Aircraft: BOEING 737, registration: G-EZJK
Injuries: 4 Uninjured.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
On January 12, 2009, at 1545 Coordinated Universal Time, an easyJet Boeing 737-73V, registered in the United Kingdom as G-EZJK, experienced a violent pitch down during flight. Vmo was exceeded by 100 knots, and a 10,000 foot loss of altitude occurred. The aircraft recovered from the maneuver and landed safely. 4 flight crewmembers were on board, and there were no passengers. None of the flight crewmembers were injured.

The investigation is being conducted by the United Kingdom's Air Accidents Investigation Branch (AAIB), and the NTSB has designated a U.S. Accredited Representative to assist the AAIB in their investigation.

[sleeper]

"Vmo was exceeded by 100 knots, "

If true this is serious and shows boeing aircraft are built like tanks.

[OLNEY 1 BRAVO]

I believe this happened during a post maintenance (end of lease) test flight out of Southend.

[captplaystation]

I believe something similar (but I think a bit less dramatic) happened on a post maintenance test flight to one of Ryanair's fleet.
One of the procedures involved ( if memory serves me well) involved disconnecting all hydraulic power to the controls in flight. If the rigging or stab position ( well something of that nature, need an engineering bod to confirm) had been misset ,the result was ,in that case ( and possibly here too) a fairly violent pitch down.
I was told by the Capt concerned it certainly gained their attention, and very importantly that of the Ryanair engineering bod on the jump seat. ( Unfortunately fo him he paid the price for his FLS colleagues gashness :D )
As discussed on other threads, " would you like to take the airframe up immediately post maintenance ? " NO THANK YOU :=

[cessna24]

Disconecting hydraulics to the flight controls is called a "Manual reversion" test. It allows you to fly the aircraft without hydraulic power to your flight controls. Its an emergency procedure for hydraulic failure.

c24

[grundyhead]

If true this is serious and shows boeing aircraft are built like tanks.

Remember the TNT 737 that "touched" down at EMA and then BHX back in 2006? Definitely tank like.

Just as solid as a Tu-154!!!!

[captplaystation]

cessna24, with 12500hrs on 737 I know what manual reversion is.
What I refer to was a procedure not dissimilar to the scenario you would find yourself in with loss of hydraulics, but was required specifically after a control surface had been repaired/removed,and, if I remember correctly, also involved switching the guarded overhead switches off too .It was I suppose, intended to give a scare when you might be half-expecting it rather than following hydraulic failure some years later.

[shortfinals]

EZY has given the basic details: EasyJet Boeing 737 plunge being investigated by AAIB and NTSB (http://www.flightglobal.com/articles/2009/01/14/321068/easyjet-boeing-737-plunge-being-investigated-by-aaib-and.html)

The AAIB is apparently silent on the matter despite NTSB opening up at least the simple facts.

[greuzi]

From Flightglobal.com

The US National Transportation Safety Board (http://www.ntsb.gov/) says it is assisting the UK Air Accidents Investigation Branch (http://www.aaib.gov.uk/home/index.cfm) in a probe of a "violent" pitch-down by a Boeing 737-700 (http://www.flightglobal.com/landingpage/boeing%20737.html) (G-EZJK) during a non-revenue flight over East Anglia, UK, on the afternoon of 12 January.
According to an NTSB preliminary incident report, the 737 was carrying four flightcrew members only when a "violent pitch down during flight" occurred. Though the pilots had recovered the aircraft and landed normally, the aircraft had exceeded its maximum operating speed (VMO) by 100kt (185km/h) and lost 10,000ft (3,000m) of altitude during the event. No-one was injured. The NTSB says the figures it has provided are subject to confirmation.
In a just-released statement: “EasyJet can confirm that we are working with the AAIB regarding an occurrence over the North Sea involving EasyJet test flight, EZY8010 from Southend to Stansted - which diverted to Southend, on the afternoon of 12 January 2009.
We can also confirm that the only people onboard the aircraft were the Captain, the First Officer and two observers. The Boeing 737-700 was being tested as part of the hand-back procedure to its leasing company.
Unfortunately, at this stage we can not provide any additional details on the occurrence as we are collaborating with the AAIB”. The AAIB has not yet responded to questions on the event.

[A-FLOOR]

That particular check is a test to see whether the balanced anti-balance (servo) tab on one of the elevators is doing its job correctly. This could very well be what they were doing as it is part of the Boeing approved acceptance test curriculum. The reason this tab is there is to provide some alleviation of the control forces in case of a total hydraulic failure.
If the linkage connecting the tab to the elevator and horizontal stabilizer is adjusted wrongly it can potentially result in a violent pitch-up or pitch-down when the hydraulics fail or are manually switched off, because the tab will start to move the elevator to an aerodynamically neutral position, much like a trim tab on smaller aircraft, except of course for the fact that this one can't be adjusted in flight. Where this neutral position is relative to the stabilizer, is defined by how the adjustable linkage is set on the ground. This job requires some extremely precise work.

[NWSRG]

If the report of 100 knots above Vmo is correct, what would that mean for the future of the airframe? What tests / inspections would be needed to determine if any damage had been done?

...and I'm sure the leasing company are a bit peeved!

[stilton]

100 Knots above VMO is a significant exceedance, I do not fly the 737 but have jumpseated a few times and would guess that would work out to about 430 kias.

I would think this would exceed even manufacturers / airworthiness testing VD ? by a major factor.

Would be interested to see how the airframe held up :eek:

[Starbear]

If the report of 100 knots above Vmo is correct, what would that mean for the future of the airframe? What tests / inspections would be needed to determine if any damage had been done?The following is an extract from a Boeing maintenance manual (not 737 but very similar type and checks will also be very similar). Its a bit lengthy but by no means complete It is also edited/cropped as well. Just skimming through should give you a very good idea of just how they go about such inspections.
You can see from the inspection title, it actually covers several conditions and not just Vmo/Mmo exceedance. I have left in the paragraph defining severe turbulence just for interest as this topic is also debated frequently on here at times.


MAINTENANCE MANUAL

SEVERE OR UNSUAL TURBULENCE, STALL BUFFETING, OR EXCEEDING DESIGN SPEED CONDITION-MAINTENANCE PRACTICES (CONDITIONAL INSPECTIONS)


1 . General
A. The structural examination in this subject is applicable after a severe
or unusual turbulence or buffet condition. It also applies to stalls
(after the initial buffet or stick shaker condition), or if the airplane
speed is more than the design speed.

(a) The pilot must make a decision if a structural inspection is
necessary.

Note: If an inspection is necessary, refer to the "Examine the
Airplane Structure" in this section.

Note: Severe turbulence is identified as turbulence which
causes large, abrupt changes in the altitude and/or
attitude. The airplane could be out of control for
short periods. It usually causes large variations in
airspeed. Passengers and crew are moved violently
against their seat belts


C. The data that follows applies to airplane speeds greater than the design
speeds:
(1) The maximum design speed of the airplane for usual flight operations
is the Maximum Operating Speed. The Maximum Operating Speed is
found in Section 1, LIMITATIONS of the airplane Flight Manual. The
aural warning horn will operate at this speed condition.
(2) If the airplane speed is 20 knots, or more than the Maximum
Operating Speed (20 knots above Vmo or 0.02 mach above Mmo), do the
Examine Airplane Structure procedure in this section.




MAINTENANCE MANUAL
(c) AIRPLANES;

Examine the fuselage, section 46 lower lobe for distortion,
paint that has flaked, and for cracks. Also look for fasteners
that have pulled out or are not there.

Note: A light skin wrinkling/buckling of the lower aft body
(between stations 1370 and 1470, below stringer 20L) is
a usual condition when the airplane is on its landing
gear. But, an apparent increase in the magnitude of
these buckling patterns is cause for more internal
inspections. This is shown by the formation of sharp
creases that usually show between the fasteners.
(d) Examine the complete empennage, section 48 for distortion,
paint that has flaked, and for cracks. Also look for fasteners
that have pulled out or are not there.
(e) If any external damage is found, do the step that follows:
1) Examine all of the internal primary structure in the
damaged areas. Look for distortion, paint that is flaked,
for cracks, and for fasteners that have pulled out or are
not there. Wrinkles in the keel beam vertical web are
normal.
(f) Examine all of the internal structure of the fuselage, section
48 that you can get access to. Look at the structure from the
rear pressure bulkhead to the aft end of the airplane. Look
for distortions, paint that has flaked, and cracks. Also look
for fasteners that have pulled out or are not there.
1) Look at areas that follow:
a) The aft fuselage bulkheads
b) The fin attach fittings
c) The horizontal stabilizer center section
d) The stabilizer hinge fittings
e) The stabilizer jackscrew-mechanism mount fittings and
support structure
2) Look at the jackscrew and hinges for signs of binding.
3) Inspect the horizontal stabilizer-to-body rubstrips. Look
for signs of movement of the structure against the
rubstrips. Such movement shows distortion of the
structure.
(g) Examine the external surfaces around the top and bottom
wing-to-body attachment. This includes the wing to body
fairing, and the rear spar web. Look for distortion, cracks,
badly chafed areas, and fasteners that have pulled out or are
not there.
(h) If external damage is seen, examine the body-to-wing joints,
and the landing gear beam-to-body joints. Also examine the
upper-wing skin splice for distortion, paint that has flaked,
cracks, and for fasteners that have pulled out or are not
there.

MAINTENANCE MANUAL
(i) Examine the external surfaces of the wing at the skin splices.
Look for misalignment and for rivets that have pulled out or
are not there.
1) Examine the external surface of the top of the wing
trailing edge for buckles in the skin.
2) If external damage is found, do the step that follows:
a) Examine all of the internal primary structure, in the
damaged area, that you can get to. Look for
distortion, skin that has buckled, cracked, and paint
that has flaked. Also look for fasteners that have
pulled out or are not there.
(j) Examine the wing control surfaces and the attachments at the
front and rear spars. Look for cracks and for rivets that are
pulled out or are not there. Also look for signs of binding.
1) If external damage is found, do the steps that follow:
a) Examine the spars for distortion, buckling, cracks, and
paint that has flaked. Also look for fasteners that
have pulled out or are not there.
b) Examine all of the internal primary structure in the
damaged area you can get to. Look for distortion,
buckling, cracks, and paint that has flaked. Also look
for fasteners that have pulled out or are not there.
(k) Examine the landing gear doors and landing gear uplocks for
damage.

S 212-011
(4) Examine the inspection and blowout doors on the lower surface of the
wing and the engine pylons. Also examine all inspection and access
doors on the lower side of the airplane body. Look for distortion,
displacement, broken latches, skin cracks and delaminations. Also
S 212-012
(5) Examine the wingtip fairings for distortion, cracks, and paint that
has flaked. Also look for fasteners that have pulled out or are not
there.
S 212-022
(6) Examine the horizontal stabilizer external surfaces for signs of
buckling. Look at the skin splices for cracks and fasteners that
have pulled out or are not there.
(a) If external damage to the horizontal stabilizer is found, do
the steps that follow:
1) Examine the spars for distortion, buckling, cracks and
paint that has flaked. Also look for fasteners that have
pulled out or are not there.
2) Examine the internal primary structure in the damaged area
you can get to. Look for distortion, buckling, cracks and
paint that has flaked. Also look for fasteners that have
pulled out or are not there.
(b) Examine the horizontal and vertical stabilizer rear spar webs.
Look for distortion, buckling, cracks, and paint that has
flaked. Also look for fasteners that have pulled out or are
not there.
(c) Examine the elevator external surfaces for cracks, fasteners
that have pulled out or are not there.
(d) Examine the elevator hinge bearings for signs of binding.
(e) Examine the elevator actuator bearings for signs of binding.
(f) If any external damage to the elevator is found, examine the
front spar web. Look for distortion, cracks, paint that has
flaked, and fasteners that have pulled out or are not there.
(g) Examine the fin external surfaces for signs of buckling. Look
at the skin splices for cracks, and fasteners that have pulled
out or are not there.
(h) If external damage to the fin is found, do the step that
follows:
1) Examine the internal primary structure in the damaged area
you can get to. Look for distortion, buckling, cracks, and
paint that has flaked. Also look for fasteners that have
pulled out or are not there.

Etc.etc

[captplaystation]

A-FLOOR,
Thanks for the clarification, that is exactly the one I was thinking of. As you say it "requires" some extremely precise work. My colleagues found out the results of imprecision.
Stilton,
That would be 440kias, think that would indeed be above VD by some margin.
Bloody impressive that they make them so tough, and I would think a fairly sterling bit of piloting to recover from that without overstressing the airframe.
A bit too close to an XL/AirNZ - plane plunges into sea on test flight -scenario for comfort.
Hope that check was indeed the cause, anything else (runaway stab) should have been nipped in the bud a bit sooner.

[Sonic Bam]

You can usually expect some pitching motion when disconnecting the hyds and there are limits of the number of units of +/- elevator trim to trim out the control forces that decide whether it is a pass or a fail for the test.

If I remember correctly, paint and balance of control surfaces does not require manual reversion flight test as suggested further up. The most common reason for calling a manual reversion test is replacement of the elevator trim tab control rods or the bearings on the tab brackets. This is a common occurence on major maintenance checks.

When the manual reversion fails on the flight test, the aircraft maintenance manual has a table that converts the number of units of trim required to the number of threads to adjust the control rod eye-end and hence rod length.

I have seen a very similar occurence to how this one is described when the elevator tab rods were adjusted following a failure of the manual reversion test on the initial flight test and the engineers carrying out the adjustment turned the eye-ends in the wrong direction. When the aircraft came back from the second flight test there was definitely a funny, not too pleasant, smell in the flight deck.

IF (repeat IF) tab rod adjustment is the cause of this occurence, I would doubt that the aircraft went into Southend for maintenance with this as an existing fault that has lain dormant until a manual reversion test was called on the hand back flight test. :(

[angels]

As discussed on other threads, " would you like to take the airframe up immediately post maintenance ? " NO THANK YOU

My dad was an 'erk' (groundcrew) in the Far East during WW2. After the war had ended and things were a little less frenetic they spent a lot of time giving war-weary aircraft a thorough going over.

The pilots would always make the ground crew come up with them on the first flight after the overhaul. "If I'm going to prang, you're coming down with me." (Obviously not with Spits etc).

Dad loved it and logged many pax hours pottering over the jungles of Malaya and Burma. :ok:

[BitMoreRightRudder]

Though the pilots had recovered the aircraft and landed normally, the aircraft had exceeded its maximum operating speed (VMO) by 100kt (185km/h) and lost 10,000ft (3,000m) of altitude during the event

I can only imagine how that must have felt for the crew. Hats off to them, the recovery from such an exceedence cannot be easy.

Out of interest, can anyone confirm what sort of altitude block is usually requested from crews during test flights in UK airspace? If they were over the North Sea I am assuming they were in controlled airspace at the time. Losing 10,000ft must be quite an experience:ooh:

[Blink182]

Manual reversion test on the 737 call for an altitude of 36000 feet. So block of airspace requested 33000-39000.
Two types of trim tab rods..aluminium or titanium , the trim limits are different for each.
Hyds are switched off, pilot tries to maintain altitude and you count the trim wheel turns to null any pitch up or down tendency.
Complicated by the "slack" in the cable system......trim wheel may have up to 3/4 turn before any effect.

[X13CDX]

.. a violent pitch down exceeding 100 knots past it vmo loosing 10,000 ft altitude.. cant imagine how frightening that must have been for the flight crew..

[White Knight]

Hats off the the flightcrew for recovering from such a violent upset:ok:

And there's me thinking it was just Airbii that bucked like broncos:E:E

[X13CDX]

.. absolutely hats off to the flight crew for recovering from such a scary attitude.. just lucky that they had enough altitude to do so, and a good job for easyjet that this wasnt a commercial flight..

[stator vane]

puts a bit of assurance in the old flight bag.

[Sonic Bam]

X13CDX
“.. a violent pitch down exceeding 100 knots past it vmo loosing 10,000 ft altitude.. cant imagine how frightening that must have been for the flight crew..”

“.. absolutely hats off to the flight crew for recovering from such a scary attitude.. just lucky that they had enough altitude to do so, and a good job for easyjet that this wasnt a commercial flight..”

Ermm, won’t that be why it is a requirement in the maintenance manual to do the (non-revenue) flight test if control rod adjustment or other designated criteria are met and usually performed by specific crew at specific height and specific flight conditions (i.e. visual horizon, etc.)?:ok:

[X13CDX]

.. Sonic Bam..

"Ermm, won’t that be why it is a requirement in the maintenance manual to do the (non-revenue) flight test if control rod adjustment or other designated criteria are met and usually performed by specific crew at specific height and specific flight conditions (i.e. visual horizon, etc.)?http://static.pprune.org/images/smilies/thumbs.gif"

.. is this not a "professional" pilots rumour network?.. therefore shouldnt critisim of someones remarks not be made constructively rather than in a negative way.. n with all the facts as to the nature of this flight not being disclosed as of yet.. shouldnt any asumptions as to maintanence carried out before the flight or not be left as asumptions for now and not spoken as if they are fact..

as for the above Stator Vane.. definately hats off the aircraft too! :)

[aviatordom]

Congratulations to the crew, who i'm sure handled the situation very well indeed:ok:

Where abouts exactly is the aircraft parked up now at Southend?

Will it be grounded until the exact cause of what happened is diagnosed?

[jimjim1]

First supersonic airliner flight for a few years?

VMO/MMO 340/0.82 (KCAS)

So +100 = 440 KCAS.

Anyone any idea what the mach number might have been?

[siftydog]

apparently 10000' might be a tad of an underestimate; some media (pretty reliable) reported 26000' height loss at an average rate of 13000fpm. defo supersonic i'd say

[Hahn]

440 IAS @ 260 = M 1.1
440 IAS @ 100 = M 0.8
My guess is closer to FL 100 because I doubt that the "tractor" will go supersonic! I´ll buy the crew a beer nevertheless!

[Starbear]

If indeed this "upset" was caused by testing manual reversion, it will be very interesting to learn if the crew recovered through sheer effort on manual controls or if perhaps they had the wherewithal and indeed the capacity under such dramatic circumstances to reinstate the hydraulics. Either way looks like a remarkable effort to recover at all.

[ortotrotel]

"Ecxceedence" is not a word. At least not in English.

[one post only!]

X13CDX, there are enough facts to know that it was a test flight and therefore the crew will know explicitly what they are doing so there is no "luck" that they had the altitude to recover. Planning!

Yes this is a "professional" pilots rumour network, enjoy the PPL training!

Certainly sounds like brown pants time.....

[White Knight]

One Post Only - yes, it was a test flight and the crew knew what they were doing... However, when the aeroplane does something that's not expected then it's no longer a test flight..
I'm sure 'manual reversion' in the 737 (can't quantify 'cos I'm not a boeing guy) is not certified to act like that:= And obviously a test flight after maintenance is to make sure it does what it's CERTIFIED to do..

Now, off YOU toddle for your PPL training:}:}

[rhythm method]

recovered at 5,000ft

That must have been damn scary, if they started at FL360. :eek:

[Sonic Bam]

X13CDX
".. is this not a "professional" pilots rumour network?.. therefore shouldnt critisim of someones remarks not be made constructively rather than in a negative way.. n with all the facts as to the nature of this flight not being disclosed as of yet.. shouldnt any asumptions as to maintanence carried out before the flight or not be left as asumptions for now and not spoken as if they are fact.."

Ermm, sorry, obviously touched a nerve.

Regarding whether maintenance before the flight is a contributory factor or not, my post said “if” and I thought I had posted quote “IF (repeat IF) control rod adjustment ….” but I acknowledge that this is not what appears in my post on the forum but my intent remains the same ….

IF this was a post maintenance flight test for hand-back to the lessor OR hand-on to the lessee or buyer OR maintenance manual requirement following tab rod adjustment, the potential failure was / should have been planned and briefed for by the crew who are “normally” trained to react to a potential failure of this test.

As a couple of other posts have said, this was an occurrence that, though very severe in nature and would initiate a “brown trousers” response in the best of us, was something that had safety in mind throughout.

It could not have occurred with pax on board.

That was the point of my post.

A further posts has suggested it took 25,000ft to recover from the disturbance – if that is true, something else has to be taken into account, in my humble opinion.

[airfoilmod]

If it started as a "test flight" but the a/c did something "unexpected", and then it was no longer a "test flight", what was it?

AF

[one post only!]

White Night, err no thats not what is supposed to happen on manual reversion. Thats why its tested though!!! To make sure it does what its supposed to and if it doesn't to sort it!! Still keeping it in the bounds of a test flight surely?!?!? If not what does it then become? A fairground ride???? Answers on a postcard!

This isn't the first time something unusual has happened on a test flight (well not this eye wateringly dramatic!!), and certainly won't be the last. Hence why the crews are selected and well trained.

Whatever, good job by the crew! And all for only 1 sector payment!!!!

[boguing]

If it started as a "test flight" but the a/c did something "unexpected", and then it was no longer a "test flight", what was it?

A trying flight?

[lurkio]

A real TEST, but not of the aircraft but of the crews ability to recover the situation?

Seems to be a lot of it about this week.

[PBY]

I am impressed with the Boeing, how sturdy it is. But I also have a question. Can Boeing be really flown in manual reversion in case of the loss of all hydraulics, as somebody mentioned? A 320 cannot do that. No hydraulics = no flight controls (not even manual reversion)

[relax.jet]

Yes u can fly B737 in manual reversion. It`s a part of test flights and sim checks.

[sjm]

Did a test flight after a 'D' check(i think) full flying surfaces removed and replaced, manual reversion part of the sign off.

Test schedule used was caa required schedule and in the briefing between myself and capt we discussed this very senario, and how to deal with it. Those in the know with experience of test flights seem to expect this possibility, and brief the following:

Allow the aircraft to pitch down/up and respond by counter acting the pitch, however the interesting part is you have to remove all control inputs and put the hydraulics back on without trying to control the aircraft before thier back on otherwise the hydraulics kick in with max pressure and opposite control forces to the pitch.

not good:O

[Rainboe]

After 10 years flying the 737, I have expressed the opinion here before that it is an emergency 'keep you in the air procedure' only. It can be flown in manual reversion with not a lot of control. Control forces are very high requiring both pilot inputs. Control is bizarre, it is impossible to fly with any degree of accuracy or logical control. I have only tried it in the simulator and have to say I dislike it intensely. I believe in a real life situation getting it down on a runway in a surviveable state is very questionable. However, it is better than nothing. At least it gives you a chance. but I do think the proportion of surviveable outcomes in such events would be in the minority.

[captplaystation]

Seem to remember way way back, Brittania landing one in GLA in Man Reversion (circa 1982? ) but maybe the memory is playing tricks. Any instructor I have had in sim who has done it for real (usually on test flts) has emphasised to me that the aircraft (whilst not easy or pleasant to fly) is a few degrees easier than the sim. I have not ( I am glad to say :suspect: ) had the chance to verify that. Will be interesting when the report is published to see if the reported 5000' level off is confirmed. That is TOO damn close to a smoking hole in the ground for comfort - and if they really started @ F360 :eek: well it doesn't bear thinking about.

[Centreline747]

IF this occurred during a check of manual reversion then why not just re-instate the hydraulics? (sjm - post 44 are you implying that you cant?
I have flown the 737 and as Rainboe commented the manual reversion training in the sim is horrible.
Thankfully, due to the redundancy on the 747, it doesn't have manual reversion; I'd hate to have to try and move those large controls manually, if you could at all!!

Well done to the crew whatever the situation was:ok:

Rgds

CL 747

[Centreline747]

Thanks. I can see that happening with control input, I just wondered if, when it all began to go pear-shaped, relax the controls, apply hydraulics, and smoothly and gently recover. I wasn't there so I don't know what happened. (Gladly)
Just my thoughts.:)

Rgds

CL747

[kriskross]

The CAA flight test schedule, in front of me, for the -300 calls for this test to be carried out at F 350. The -700 test requires this to be done at F150, so that would be a 10000ft height loss for a 5000ft recovery

[Checkboard]

The height loss was about 10,000 feet, recovery was nowhere near 5000 AGL. The height loss was so large because you have to unload the controls in order to re-instate the hydraulics, and even with a 90 degree roll, the initial pitch has dropped the nose quite a bit. Once the aircraft is in overspeed, the the nose up recovery needs to be gentle in order to avoid a worse overstress.

[Smilin_Ed]

Is everyone assuming that every pitch change would be up into a stall? Could it not be down? :confused:

[Mr Good Cat]

Not meaning to drift the thread but the 737 CAN be flown with some degree of accuracy in Manual Reversion, providing you still have the standby reservoir available.

This is from both sim experience AND flight test experience. Any lack of authority from the ailerons can be supplemented with inputs from the now over-sensitive rudder. Yes, I agree that situations such as gusting crosswinds may limit controlled landing techniques but generally it's not the end of the world and it is definitely controllable with one pilot's inputs only - and this is from a puny midget!

The problems arise in scenarios like the one being discussed. A similar occurrence happened to me on a air test a few years back when I was just a wee cadet in the RHS. We took an EZY classic up over the Irish Sea west of the Hebs after a replaced elevator and switched off the flight controls, after which we experienced several seconds of weightlessness and about 4000 feet loss of altitude until we could get the switches back to their rightful positions. The elevator was only two thousands of an inch out, but this was enough to upset things in a BIG way...

[veterangreaser]

PBY
Ask the captain of the AA A320 about no engines and aircraft control! No engine hydraulics, just the blue system powered by the RAT? He seemed in full control to do such a good job! The 737 is still a great aircraft, BUT underneath the recently added "Bells & Whistles" it's still 40 year old technology.:=

[wkw198]

think it was US Air not American Airlines (AA)

[ciampino]

I know this is a NG but the 300 MM states DO NOT REINSTALL HYDRAULICS

[Papa Golf]

A-Frame is correct, very small adjustments of the elevator tabs can have quite a large trim impact in manual reversion. Most common error is not a gross error as with EZY but making the adjustment in the wrong direction (the Boeing Maintenance Manual had to be followed very carefully to get it right). Some years ago have seen Boeing adjust tabs in wrong sense on new production aircraft during flight testing prior to customer acceptance.

[Fliifast1]

Hey, my company is getting a -700 from EasyJet in two weeks...I'll let you all know how she trims out. Fli

[Tee Emm]

Control forces are very high requiring both pilot inputs

According to Boeing in Seattle, there is no non-normal manoevre in the FCTM that requires the use of two pilots on the controls. If there was, three pilots would have to constitute the normal crew in case one became incapacitated. The manual reversion approach and landing is relatively straight forward to fly assuming a competent pilot is flying. Some operators prefer that one pilot flies the manual approach and the other pilot handles the power. It was this policy that aroused the ire of simulator instructors at Seattle.

Some pilots have done only one manual reversion approach and landing as part of a typre rating then never practiced one again. It is these pilots that may experience significant handling problems and then complain of the danger. One pilot can easily fly the approach and handle his own power IF he is competent. Automation complacency has a lot to answer for - especially where almost total reliance on automation has led to a class of pilots that have lost confidence in their ability to handle something like a manual reversion landing.

[Chille Con Carnie]

G-EZJK had another test flight yesterday understand no probs--- with handling?

[charliemouse]

PBY
Ask the captain of the AA A320 about no engines and aircraft control! No engine hydraulics, just the blue system powered by the RAT? He seemed in full control to do such a good job! The 737 is still a great aircraft, BUT underneath the recently added "Bells & Whistles" it's still 40 year old technology.:=

The first thing Sully did was start the APU - so this not relevant?

[6853]

Anything official yet?

[a300dave]

G-EZJK now reregistered and winging its way to Brazil

[Jofm5]

For those that are interested AAIB Special report into the incident is available from Air Accidents Investigation: S2/2009 - Boeing 737-73V, G-EZJK (http://www.aaib.gov.uk/publications/special_bulletins/s2_2009___boeing_737_73v__g_ezjk.cfm)


Cheers all

[rhythm method]

The commander rolled the wings level and attempted to arrest the rate of descent which had increased considerably, peaking at 21,000 fpm; the aircraft had pitched 30° nose down after the aircraft had been rolled to the left.

Nasty! :eek:

[OneOffDave]

With typical restraint, the local press here have covered the story in today's paper as "Airliner in terror plunge over Norfolk".

[Whiskey Zulu]

Dave, on this occasion, the headline actually seems justified?

[Jonty]

Apparently it pulled out of the dive at 5600ft as it entered a layer of cloud.

I would have needed new trousers after that little "upset" :}:}

[dieseldo]

I believe this is the second time this has happened to an EJ aircraft.Last time was 4-5 years ago on airtest out of a heavy maintenance facility in France post C check.I understand that reinstating the hydraulics without off loading the stabiliser/elevators by banking could lead to loss of the control surfaces.Huge well done to the crew.

[captplaystation]

Maybe I need to get back in the sim and practice, but I don't see that you are doing yourself any favours in terms of further airspeed increase by rolling to 91 degree of bank in preference to just momentarily releasing the controls and re-instating the hydraulics at that point. Maybe more chance of your colleague re-instating the switches promptly as his eyes might be open rather than closed at the sight of a 91 degree bank angle via Boeings " letter-box". :eek:
I guess in theory the bank angle "should" help contain it, but the time spent rolling & then unrolling the aircraft might be better spent just promptly unloading/reinstating HYD power ASAP ? Just my feeling.
Tough old Bird the 737 :ok: 440 . . . Vmo plus 100 phew :D

[Mungo Man]

With typical restraint, the local press here have covered the story in today's paper as "Airliner in terror plunge over Norfolk".

What's not a 'plunge' about 21,000fpm ROD and what's not 'terror' about pulling out at 5,600ft?!

[Permafrost_ATPL]

The 90 degree bank manoeuvre is in the CAA test flight guidelines. The NG QRH seems to agree with that for a pitch up attitude (see Upset Recovery), but definitely not for pitch down. The main concern when turning the hydraulics back on is to have your hands off the controls to avoid overstressing the surfaces and linkages when the pressure comes back. The 90 degree bank has more to do with regaining airspeed (as opposed to trying to offload the wings). So the CAA's guideline to apply that bank in the case of any loss of control during manual reversion seems questionable.

It was a 'favour' that probably saved their lives - I don't think they had the altitude to offload the controls again . . .


What saved their lives was the airspeed increasing to a point that they had enough elevator authority to pull up. The captain was not aware that the hydraulics were not back on...

A lot to be learned from that incident.

P

[GAZIN]

"If it aint broke don't fix it!"
The aircraft was within limits on the previous flight & there was no write up.:ugh:
Thank goodness nobody was needlessly hurt.

[fireflybob]

I see the media are using that word "plummeting" again!!

[HarryMann]

The 90 degree bank has more to do with regaining airspeed (as opposed to trying to offload the wings). So the CAA's guideline to apply that bank in the case of any loss of control during manual reversion seems questionable.Seems some confusion here... would imagine that procedure is indeed for nose-up out of trim, NOT in a rollercoaster dive.
Why?

A potential 'rolling pullup' - this is what probably broke Concordski (Tu144) at Paris.
'Do the sums' I suppose is the phrase...

The normal loads on the upcoming wing combined with pitchup loading, 'sum together', so a much greater chance of overstressing and breaking the aircraft.

In short, you ar more likely to overstress the upcoming wing.

[Permafrost_ATPL]

I just found the CAA document on check flights (http://www.caa.co.uk/docs/1455/CheckFlightHandbookIssue2Point1-February2009.pdf).

This is the relevant paragraph:

Always, RELEASE ANY FORCES that you are holding before re-powering a flight-control system, even if by doing so the aircraft will enter an unusual attitude. It might be possible to put some bank on the aircraft to turn a large pitch-up into a turn manoeuvre before re-powering the system. For a pitch nose-down, it is essential to maintain wings level whilst recovering to the horizon before re- instating power to the controls.

Interestingly, most of that document dates from May 2008. One exception: the part that covers test flights of large aircraft - dating February 2009. I wonder what changed :} Anybody has the pre-February version?

P

[HarryMann]

For a pitch nose-down, it is essential to maintain wings level whilst recovering to the horizon before re- instating power to the controls.

Exactly!



... apparently exactly! is not 10 characters so insufficient for a response (too much automation!), so i shall just say, reinforcing my point above about rolling pullups

[Sonic Bam]

I'm surprised at the test being required at FL150, I recall it used to be done at FL350+, but I could be wrong. Why would it be specified to carry out the test at FL150 when you could have another 20,000' for recovery if something went wrong?

With regard to the shakedown flight, the manual reversion being just within limits and then calling for rectification, this is not unfeasible or beyond comprehension.

On the customer acceptance flight test following the maintenance input, if the test was just within tolerances when performed on the shakedown it might have been just outside tolerances on the customer acceptance flight test and you are then required to carry out adjustment of the tab control rods on the ground and fly the aircraft again - more cost. Also, it is usual for the engines to be boroscoped after the flight test and further work carried out if there is an immediate handback planned (re-registration, replacement of a/c data plate, Mode S ident reprogramming, etc.). It is a reasonable decision to get the tab rods inspected and adjusted on the maintenace input to reduce risk of the customer acceptance flight test failing and possibly upsetting any plans in place for the post flight test maintenance and hand-over of the aircraft to the owner.

What is not reasonable is not to write it up in the log so that it can be transferred to the maintenance documentation accurately. It has to be assumed that the manual reversion results were recorded on the "shakedown" flight test documentation and this passed to the engineering organisation but I will be very surprised if this is not, at least, commented upon in the final report.

[scousegit]

Having just read this forum and the AAIB report, there are a number of issues to be accounted for and a number of people who questions should be aimed at.

I'm also amazed (or not really) by the number of people who have absolutely NO idea what they're talking about posting views on this site although it is rumour network.

Let’s begin at the beginning.

The crew flew the aircraft to the MRO and carried out a pre-maint shakedown. They were not happy with the manual reversion limits. The CAPTAIN on arriving at the MRO should have been debriefed not only by the accepting engineering staff but also present should have been the Lease agent (Owner) and any questions and irregularities be discussed. Any defects should have been entered into the aircraft Tech Log and then eventually transferred into the aircraft input checkpackage as an incoming defect. This way nothing gets missed and all entries have to be completed and certified prior to the next flight by a suitably qualified engineer. The manual reversion in this case was just within the AMM limits although the owner may have a contractual agreement with the lessor as to the return conditions in this case so adjustment would have to be in agreement with the lessor, owner and MRO for commercial purposes. IT STILL NEEDS TO BE WRITTEN IN THE LOG!!

OK, following the input and the return conditions complied with, (the Lessee may also insist on a wider AMM limitation with agreement from the owner/MRO) as required in the AMM for either the adjustment of both Tab rods, the removal of the elevator tab and replacement of any hinge or the replacement of BOTH rods/eye end bearings a manual reversion test flight is required iaw 27-31-00.

In our company a management flight crew and a licensed engineer type rated and approved is the minimum crew allowed to carry out this flight test. The pilots fly and the engineer sits on the jump seat and controls the hydraulic input in conjunction with the crew. This means the pilots can control anything that may happen and not have to worry about reaching behind and overhead for the hyds. Why was an engineer not present on this flight???? This seems almost certainly a question that needs to be answered and incredibly dangerous for a situation as described here where the Co-Pilot is struggling and communications are not good in a frightening experience.

Make no mistake the crew did exceptionally well here and it could have been all-so-different but in my view an engineer should have been provided by Ezy as effectively they were still the lessor until the completion of a successful test flight thereby transferring to the new end user.

I can't comment on the recovery or the practices used in recovering the aircraft in this situation, I'm not a pilot and wouldn't judge what they did. I have however accepted and delivered many aircraft as an engineer and carried out my last flight test last week following post maintenance and have done numerous manual reversions on both the 73Cl and 73NG so I can only comment on what I have a knowledge of. I have also been a check manager/crew chief responsible for heavy inputs for a number of MRO's and major airlines and have leased/disposed of aircraft as a technical representative for a number of airlines/lease companies.

So my 2 basic questions are, (1) Why wasn't anything recorded by the inbound crew?? (Big Mistake by the Capt) . If its on paper it has to be certified and (2) Why didn't the company/Airline (Ezy in this case)/MRO provide and engineer to act as an additional crew member to allow the flight crew to deal with a potentially difficult situation as this has to be expected when carrying out a manual reversion test??

These flight tests are carried out quite often and are depicted in the AMM is to the reasons why. These reasons are quite specific and controlled and are there to ensure when the loss of Hyd's (Sys A+B) the aircraft is still controllable and the flight test criteria is also quite specific and controlled. They are also definitely NON REVENUE and in specific airspace previously agreed beforehand so it isn't just something anyone can jump in and do (To the uninitiated out there!!). It is part of an engineering procedure in case of a flight eventuality you hope is never going to happen.

Following the failure of the test flight the AMM would have been consulted and the adjustments made as required in accordance with the AMM procedure. The adjustments in this case were incorrect and made in the wrong direction which is an easy mistake to make but should have been picked up on the duplicate inspection. (At this point the company QA dept should be involved with this incident and ask the questions why the procedure of correction went so wrong). I sympathise with the engineers involved and can see how the mistake was made. BA at GLA a few years ago turned a 73Cl into an orbital spaceshuttle by making just this mistake so as you can see it can happen anywhere, has done before and will do again.

Normally once the adjustments have taken place no further flight test is required although this is at the discretion the companies concerned.

I hope this may go some way to answering some of the more outward posts placed here.

[moosp]

Jofm5 thank you for the link to the AAI link, much appreciated, so we can see who knew what they were talking about over the last couple of months and who was way into spacey stuff. A re-read of the thread will educate us all as to who are the smart cookies here.

An interesting report, with very minor recommendations. That usually means that those involved were doing the right thing, and through their superior airmanship managed to save the day.

This was a test flight, and it was resolved to a safe landing. Although the AAI cannot write it, by their conclusions and limited recommendations they are saying well done. And that is the highest accolade you will ever get from the AAI.

And to those who thought terror and plunge were acceptable descriptions of what occurred you do not understand flight tests and the character of those who do them. You do however understand journalism.

Minor whinge here. When are you guys at the AAI going to get digital and produce your reports in a single column? Double column reports are difficult to read on screen and went out with MADMEN.

[captplaystation]

scousegit,
I am somewhat surprised by your assertion that "Normally once the adjustments have taken place no further test flight is required" . . in this case what is the safeguard against someone turning the thingy (tech description on my part :rolleyes: ) the wrong way, or too far ?
I thought I read that it is a very delicate process to get the position "just so ", are you saying that after it is adjusted it doesn't have to be reflown again & the first one to find out any misadjustment is some poor sod a few months down the line who has a HYD failure, or. . . (not entirely impossibly ;) ) am I missing /misinterpreting something you said ?

[daisy120]

Yes but with typical editorial mishandling, the lead article in the EDP had a pic of an Easy A320. When questioned this morning, the news desk lackie said, "thought I should have confirmed the aircraft type before we went to print"!:yuk:

[HarryMann]

Anything can help bring an aircraft down (more so these days it seems due to automation/complexity/interconnectedness) but control surface/trim/servo tabs are so critical that if there is any doubt in the mechanics or inspector's mind of degree or sense(direction) of adjustment, surely eat humble pie and get Boeing to fax more explicit instructions. Check and double check with your peers and supervisors.

I also find it somewhat surprising that there isn't a call in this procedure for a way to check pre-existing power-trim forces (excessive) before pulling the hydrualics, to avoid going from the frying pan into fire. e.g. a quick and dirty check on how hard the powered systems are working

[scousegit]

CPS,

Sorry my mistake the AMM has now been revised and the statement is now as follows -

Make sure that you satisfy the flight test requirement before a revenue service of the airplane.

However, if it is not possible to perform a flight test before revenue service, you can operate the airplane in revenue service for a maximum of 10 days before you successfully complete the flight test.
A second flight test is necessary if the pitch up or pitch down trim is more than the limit during the first flight test.

However to obtain a CRS following an engineering input you would need to carry out at least 1 flight test. the adjustments can then be made and the next flight test can be defered for a maximum of 10 days.

My apologies.

[ericferret]

So it fails the first flight test by more than the number of trim wheel turns allowed. Engineering then makes an adjustment in the wrong direction making the situation worse.
You can then fly around for ten days with this unknown quantity on revenue.

Dear Lord please ensure I am not a passenger on this aircraft!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Out of interest I saw 737-300 come off C check during the winter (short days) which failed the initial check. The engineers adjusted the wrong way and the first days airtest daylight was lost. As they were then unsure of the position they then rigged from scratch.
It failed again and a second adjustment was made. It failed again (just) and the second days flying was over. Passed at the 5th time of asking.

Two and a half days late off C check and the operator not happy, but the aircraft was safe.

[CaptainSandL]

There are a number of factual inaccuracies in the AAIB Special Bulletin in the last paragraph of the Engineering Investigation section.
1. Following the flight, the commander did not verbally (or in any other way) request that this be addressed. He merely reported his observations verbally and in the flight test report to the engineering rep for engineering to decide if rectification should be made.
2. He elected not to enter it in the tech log because as it was within limits it was not a defect. This is standard procedure. He did however record it as an observation on the Flight Test Schedule.
3. There was a formal written record. The commander gave the original 28 page flight test report, which contained the shakedown manual reversion observations, to the engineering rep.

I expect these errors will be corrected in the final report.

[Greek God]

The commander stated that, should the aircraft pitch up or down uncontrollably during a manual reversion check, he had been trained to roll the aircraft to unload the pressure on the elevator and release the controls before reinstating the hydraulics. The commander therefore, rolled the aircraft left 91.2°

Why o why would you roll 90degrees when in a relatively benign nose down (-2.81deg) situation? A roll should be used only in a nose up situation to limit the nose up and allow the nose to drop by being in a turn. Having said that top kudos for the subsequent recovery - 20 000ft/min = not a lot of time to the deck & a real possibility of inducing structual failure at Vne+100kts

[ajamieson]

There are a number of factual inaccuracies in the AAIB Special Bulletin in the last paragraph of the Engineering Investigation section. I expect these errors will be corrected in the final report.
Very interesting, and a serious accusation. This is fundamental to the conclusion of the report as I read it. If you know what you claim to know, I presume you have made the AAIB aware of the error?

[NigelOnDraft]

There are a number of factual inaccuracies in the AAIB Special Bulletin in the last paragraph of the Engineering Investigation section. I expect these errors will be corrected in the final report.

Very interesting, and a serious accusation. This is fundamental to the conclusion of the report as I read it. If you know what you claim to know, I presume you have made the AAIB aware of the error?

ajamieson

Please re-read the notes at the bottom of p1 of the Bulletin. It is a not a "Formal Report" - it is an (interim) "Bulletin". It makes no conclusions (whereas you say it does?), no analysis section, and is all subject to change.

AAIB Formal Reports go through various consulatatons prior publication, I am not sure Bulletins do in the same way? So any inaccuracies asserted by interested/affected parties can be examined and corrected if required.

NoD

[ajamieson]

No, I never said the report had made conclusions.

I do understand the purpose of the bulletin. As I read it, the account of the facts as expressed by CaptainSandL would lead to a very different conclusion IN THE REPORT from one based on the very different account that has been published so far. You describe these differences as "any inaccuracies" as if it were a matter of correcting an isolated factual error. What CaptainSandL disputes is crucial to causal chain. Would the AAIB not already have taken such different accounts into consideration at this stage? That is exactly why I asked if CaptainSandL had discussed this with the AAIB.

[The Mad Russian]

I could highly recommend the Empire Test Pilot's School, Boscombe Down – Civil Airworthiness Flight Test Course for any pilot or engineer involved in maintenance test flying, a truly excellent course, taught by experienced test pilot instructors from this highly respected school.

They teach the correct recovery from a nose low upset...

[Expressflight]

It is reported on a Yahoo Southend Airport forum that the Captain of the 'shakedown' flight passed the request for adjustment of the trim tabs to the Easyjet engineering rep at Southend and that he wrote out the request for adjustments to be made by the sub-contracted MRO. This report states that he misunderstood the sense in which the actuator rods needed adjustment and that the MRO did, in fact, carry out the work as requested unaware that the out of trim was the reverse of what they hade been told.
I cannot vouch for the veracity of this report in any way, I'm merely passing on what is being said on that website.

[GiveMeABreak]

Expressflight,

Maybe you should have read the AIB bulletin before posting, that's where they got the 'scoop' from......

[Planeless]

daisy120-I wonder if thats the same Eastern Daily Press that last week described a 78 Seat DHC 8 Turboprop as a 40 seat DCH 8 Jet ?

[Expressflight]

GiveMeABreak

No it isn't.

I have read the AAIB report thanks and it doesn't give that information. The interim report leaves very much open the possibility that the MRO made an error, whereas the contributor to the Southend forum refutes this, saying:

"....the on-site "sub-contracted" Easyjet representative raised a written "Customer Request" to the MRO, based upon the verbal handover and made the fundamental error that the required rectification was totally opposite to that reported by the crew. The MRO rectified the defect as reported."

Whether or not those are the true facts I don't know, although the writer does seem to have some knowledge of the events from the MRO's perspective, but it certainly is additional information to that contained in the interim AAIB report.

We shall see what the truth of the matter is when the final report comes out won't we?

[ericferret]

Most airtest proformas have a section for defects. Any adjustments required should have been entered there. Failing that a tech log entry should have been made and really both documents should have been used.

Nobody should be making adjustments to flying controls based on third party information.

[HarryMann]

Nobody should be making adjustments to flying controls based on third party information

Indeed! Horrified - if there is any truth in this handover process at all...