Unserviceabilities with Unusual Symptoms ..
Joined: Apr 2004
Posts: 775
Likes: 2
From: near EDDF
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?
Anyway...
737CL:
AMM 29-15-00 PB101
737NG:
FIM 29-10 TASK 807 (Fault Code 291 080 00)
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?
Anyway...
737CL:
AMM 29-15-00 PB101
737NG:
FIM 29-10 TASK 807 (Fault Code 291 080 00)
Joined: Nov 2000
Posts: 480
Likes: 0
From: Scandiland
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.
Joined: Dec 2003
Posts: 553
Likes: 16
From: UK
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.
Joined: Mar 2007
Posts: 36
Likes: 0
From: Namibia
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.
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.
Joined: Sep 2003
Posts: 502
Likes: 17
From: Dunnunda
A320
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.
Cause: Associated engine oil pressure switch fault. That's right OIL pressure switch.
Last edited by Bula; 17th March 2013 at 20:54.
Joined: Feb 2001
Posts: 178
Likes: 0
From: right here inside my head
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.
Cause: Associated engine oil pressure switch fault. That's right OIL pressure switch.
Joined: Nov 1999
Aviation Qualifications: ATPL
Posts: 3,144
Likes: 741
From: UK
020
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.
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.
Joined: Dec 2005
Posts: 38
Likes: 1
From: Australia
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.
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 September 2013 at 11:19.
Joined: Jun 2006
Posts: 16
Likes: 0
From: Around and about
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
ParkBrake RELEASE
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!
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
ParkBrake RELEASE
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 November 2013 at 12:11.
Joined: May 2012
Posts: 18
Likes: 0
From: UK
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!
Joined: Sep 2008
Posts: 195
Likes: 0
From: In the land of smog
Chaffed Wire
A320
Dispatched with Engine 2 Igniter System A inop under MEL - requiring manual start. The flight was normal until landing.
Symptoms:
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.
Symptoms:
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.
Dispatched with Engine 2 Igniter System A inop under MEL - requiring manual start. The flight was normal until landing.
Symptoms:
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.
Symptoms:
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.
Joined: Jun 2002
Posts: 3
Likes: 5
From: Wor Yerm
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.
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.
Joined: Oct 2013
Posts: 87
Likes: 4
From: Victoria
Incorrect fueling causes engine malfunction.
ALLEGED EVENTS:
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 Ï 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.....
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 Ï 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.....
Joined: Sep 2011
Posts: 350
Likes: 147
From: FL390
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.
Cause: Associated engine oil pressure switch fault. That's right OIL pressure switch.
* CVR ground control mode will not latch on
* Multiple and spurious probe heat fault cautions on ground (reset of all 3 PHC cures).
Joined: May 2010
Posts: 645
Likes: 0
From: europe
WHY IS THIS STILL A STICKY??
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!
Sorry John, a great idea, but like Jeremy Corbyn, one that didn't work according to the plan!
Joined: Feb 2015
Posts: 103
Likes: 0
From: Middle East
320
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
- 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