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Unserviceabilities with Unusual Symptoms ..

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Unserviceabilities with Unusual Symptoms ..

Old 3rd Apr 2011, 16:03
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A more detailed description would be helpful.
Classic or NG?
During final approach (select LG down) or during landing roll (brake system in operation)?
Is the system pressure A and B the same?

AMM 29-15-00 PB101

FIM 29-10 TASK 807 (Fault Code 291 080 00)
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Old 3rd Apr 2011, 21:56
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It is classic but ok i will try to find by myself, thank you
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Old 4th Apr 2011, 06:38
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Originally Posted by vd8
...but ok i will try to find by myself...
What do you expect without giving details. Garbage in leads to garbage out.
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Old 27th Jun 2011, 12:07
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The idea of having this thread going is great, but quite frankly, it's not very useful as long as all types are mixed like this. Pprune should really consider having a separate forum area (perhaps inside of techlog) with separate threads for each aircraft mentioned. That way, type specific discussions would be kept cleaner and easier to browse through.
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Old 3rd Aug 2011, 23:11
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vd8, re 737 Classic Hyd fluid transfer. A very common occurrence on the 73.In theory fluid transfer should be impossible,but a couple of leaking vlvs cause the problem. Speak to your local engs,there are two methods used on the ground to re-establish levels. If you can't get an answer,PM me & I'll dig the full info out.
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Old 26th Dec 2011, 08:24
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Leaking ASI

Some more details?
Is this peculiar to the BE20 or does it affect the 90 / 1900 for example, is there something special about the system or could it potentially affect any pressurised/non pressurised aircraft? How does the error appear through the range, and is it only one ASI affected? I'm curious, sounds like a good one to try in the sim.
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Old 27th Feb 2013, 20:59
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Good evening/morning/afternoon,

could somebody tell me what a ''control column/yoke jam'' means?

Thanks in advance
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Old 17th Mar 2013, 20:53
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Blue and Green or Blue and Yellow HYD fault light flashing on OVHD with no associated ECAM.

Cause: Associated engine oil pressure switch fault. That's right OIL pressure switch.

Last edited by Bula; 17th Mar 2013 at 20:54.
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Old 17th Mar 2013, 22:43
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Blue and Green or Blue and Yellow HYD fault light flashing on OVHD with no associated ECAM.
Cause: Associated engine oil pressure switch fault. That's right OIL pressure switch.
Airbag uses signal from engine oil px to tell other systems when the engine is running.... So perhaps, no signal from switch meant the ptu was armed, but not running since the edp was doing just fine... hence fault light but no action required?
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Old 13th May 2013, 10:22
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Interesting thread - only just looked at it.

Regarding PB switches not turning on/off with too brief a push: A lot of electronic circuits now incorporate "de-bounce" logic into their switching. A mechanical electric switch can obviously only be on or off, but sometimes as it is operated, the contacts can bounce, causing several on/offs to occur within microseconds of each other. This is not a problem with say a simple light or a fan, but now that many systems are computer interfaced, a rapid sequence of on/offs can totally confuse a system. Therefore, many switches use de-bounce logic which ignore rapid changes and only register longer term changes.

This is not such a problem with toggle switches, but can be with Airbus pushbutton types. My Airbus training reinforced this by telling me to make (relatively) slow , positive selections on the pushbuttons, and wait to see the integral caption light go on before releasing pressure on the switch.

Even so, I have recently had a yellow pump refuse to switch off via the push button until I tried slowly several times - think this was a fault though.
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Old 5th Aug 2013, 11:23
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vd8 During flight and especially landing hydraulic fluid transfer from B to A. It became 100 A and 85 B. No leak found

I thought that was normal on 73 classic? Qty changes when gear position changes on A system.

On 73Ng a particular pseu fault can cause the gear transfer unit to operate and send B system fluid/pressure to drive the gear and "over flow" A sys to the point of it dumping the excess overboard.
In the case I saw the PSEU had incorrectly sensed an eng failure.

Black magic in that PSEU ! Be careful.

Last edited by kookaburra; 5th Sep 2013 at 11:19.
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Old 6th Sep 2013, 17:13
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Hydrolic transfer B737NG

In response to VD8 his question, altough a bit late (only just read it now), maybe this is what you are looking for:

When accepting the aircraft and finding the hydraulic quantity indication over maximum (106% on the NG) in e.g. System A:

To transfer from system A to B:
ELEC A pump ON
ParkBrake SET
ELEC A pump OFF (pressure drop)
ELEC B pump ON
ELEC B pump OFF (pressure drop)

repeat as needed (usually 3-4 times suffice)

Although this was an overfull SYS B, an overfilled hydraulic system has at least once led to an evacuation after vacating the runway, putting the flaps to up, causing hydraulic vapor to enter the cabin (check valve failure). Bad press and very sick customers.

As correctly pointed out, quantity indications vary with configuration and with diff temperatures, and fluid does seem to travel from system to system.

Good thread!

Last edited by Jetdriver; 7th Nov 2013 at 12:11.
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Old 7th Nov 2013, 09:49
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RB211 B757

Several years ago starting at SSH, right started normally and during the left engine start, the right just wound down. Both the EEC and ELC had failed. Trying to make any sense of the EICAS was not easy! Something to do with the small dedicated gen on the engine used just for the EEC, I think. No doubt someone will correct me if I'm wrong!
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Old 6th Feb 2014, 07:04
  #74 (permalink)  
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Chaffed Wire


Dispatched with Engine 2 Igniter System A inop under MEL - requiring manual start. The flight was normal until landing.


During landing with full reverse, an ECAM ENG 2 REV FAULT occurred but the reverser operated normally with no asymmetry.

After landing the APU failed to start and gave an ECAM APU FAULT - APU AUTO SHUTDOWN

On stand, ground power was supplied but tripped off after shutdown and was restored a few seconds later. As the power came on a long series of cautions and warnings appeared on the ECAM, most of which we attributed to the power transfer.

Maintenance action:

APU igniter box fault was deferred and ENG 2 Reverser was locked out.

Departure Attempt 1:

An external air manual start was conducted to a stable idle condition, then a bunch of things happened.


Then an ECAM ELAC 1 PITCH FAULT occurred, followed by ENG 2 REV FAULT and Engine two Oil pressure indication was lost from the System Display.

Maintenance Action Two:

Engine 2 No4 bearing oil pressure sensor found to be U/S with C/B popped, it was deferred in the tech log.

All flight control power supplies were reset.

Departure Attempt 2:

Engine two started the same way to a stable idle condition then a series of ECAM warnings occurred,

ELAC 1 PITCH FAULT - pilot reset; then

MASTER WARNING ELEV L + R FAULT, ENG 2 REV FAULT, SDAC FAULT and a few others I can't remember - engineer guided resets carried out to no avail.

Maintenance action three:

ELAC 1 suspected to be faulty, deactivated and all other computers reset.

The engineers advised there would be a bunch of faults but they would be spurious and can be reset.

Departure attempt 3:

After start: MASTER WARNING ELEV L + R FAULT occurred but cleared after ELAC 2 and SEC 1, 2 & 3 resets carried out.

The flight control check was normal and the flight proceeded normally albeit 4 hours late with very angry pax.

Solution (finally found a few days later):

ELAC 1 was suspected and after deactivation stopped all of the warnings but after all flight control computers were replaced the problem reoccurred! Further investigation found a chaffed wire (IIRC between ENG 2 and ELAC 1) was shorting out the computers.
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Old 27th Mar 2014, 21:51
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Type: F27-500

Symptom: Knocking noise heard in climb after cleaning up and thumping felt through control column. Frequency increased during cruise and reached maximum intensity during the descent. The instant the flap was lowered, the knocking stopped. Over a month or so, the knocking got worse and worse. Cabin crew continually complaining about the bumping.

Problem 1: There was a huge hole on the leading edge of the right hand horizontal stabliser (under the de-icing boot), big enough to stick your head and shoulders through.

Problem 2: Three of the bolts used to hold the tailplane had "gone".

Solution: Replace entire tailplane.
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Old 18th Oct 2014, 02:11
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Seemed like a good idea, but is this thread really working as intended? Should it still be a sticky after so many years, with so few posts, and even less on the same topic?
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Old 11th Nov 2014, 06:09
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Incorrect fueling causes engine malfunction.


Aircraft Type TECNAM:
Symptoms: Engine rough running and allegedly stopped in flight:
Reason: Fuel was found to be contaminated with brownish liquid which smelt unusual and looked like diesel.

What went wrong:
Allegedly the drum of fuel used to fuel the Rotex engine with the approved ULP was contaminated with diesel apparently incorrectly decanted into the service station tanks.
The fuel transferred to the aircraft was not noticed to smell wrong or the wrong colour and plane was allegedly flown and suffered engine failure.
Obviously the filter, drain, view and checks before flight did not flag the contamination.

How was it fixed
Engine strip and apparently fixed after suffering detonation issues.

A radio call stating have an emergency was heard on the local frequ:
When police went to the ad no sign of anyone or any plane was found.

So all these events may not have ever happened...it is alleged.

Don't shoot the messenger.....
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Old 27th Jun 2015, 12:39
  #78 (permalink)  
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Blue and Green or Blue and Yellow HYD fault light flashing on OVHD with no associated ECAM.

Cause: Associated engine oil pressure switch fault. That's right OIL pressure switch.
Associated faults:

* CVR ground control mode will not latch on
* Multiple and spurious probe heat fault cautions on ground (reset of all 3 PHC cures).
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Old 29th Sep 2015, 18:24
  #79 (permalink)  
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Un-used thread of zero value. Especially when considering the thread rules (another sticky) which state: It would be appreciated if folk could be a little discriminating in starting new threads and keep Tech Log for the more involved questions.

Sorry John, a great idea, but like Jeremy Corbyn, one that didn't work according to the plan!
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Old 13th Dec 2016, 15:25
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AIR Wing BLEED LEAK during engine start

- Recurrent problem in hot condition (in spite Airbus recommendation to keep Flap1 at the gate)

- MEL is no go

- We selected Flaps 3 during the "After start Flow" ECAM disappeared a few minutes later during taxi
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