Fuel Leak

[BuzzLightyears]

How would you recognize/identified a fuel leak in your airplane and what will be the subsequent considerations/actions?

[captjns]

Indications of a fuel leak may include, but not be limited to:

Abnormal decrease in fuel quantity;
If aircraft equipped with an FMC, you may get "Using RSV Fuel", or "Insufficient Fuel", or "Check FMC Fuel Quantity" message.
Fuel spraying from the engine strut or trailing edge of the wing, depending on where the fuel leak is.

Actions to be taken depend on your company's non normal procedures.

However, usually, common sense prevails, and landing at the nearest suitable airport is probably recommended.

[hawker750]

One of the symptoms that was missed by the Canadian A330 crew that ran out of fuel over the Atlantic was an abnormally low oil temperature of the engine on the side with a leak. The reason: an unnaturally higher than normal fuel flow through the oil cooler. A good lesson to be learned: unless you know why something is indicating differently to normal then it is probably telling you something.

[BelArgUSA]

For the Canadian A330 - It was not covered by their QRH (or SOPs).
It depended on system knoweldge and troubleshooting.
Have a look at the opinions that the "QRH is enough"...
Do not investigate "outside of SOP" attitude.
Ditching and swimming procedures are in the QRH - Fuel leaks are not.
See "A330 T/O thrust" discussion running presently in the Tech Forum.
xxx
:*
Happy contrails

[hawker750]

Bel
My attitude completely, it is all "by thebook" now and very little thought outside the box. I am all for the book but it is only a guide. But you and I are thought to be old f,,,ts now and that basic airmanship has no place in the modern world of QRH's and SOP's
Still those Canadians very nearly got wet!

[18-Wheeler]

I agree with BelArgUSA as well - More than a fair chunk of the problems I've had in aeroplanes have had no checklist actions to run.
Only systems knowledge and good crew coordination & management has helped us solve the problem.

[justintime5]

Apart form a big smelly puddle under your plane you can also know there is fuel leak by using your operational flight plan. This can give you a clear indication that something is not going as it should. All these guys that don't even fly with an operational flight plan are pretty brave. :uhoh: This will not only work for fuel leek but changing conditions that will take you to a situation where the fuel at destination is not good enough.

A good track of fuel and time on a plog is the best early warning on something not working well. :ok:

[vipero]

a large puddle under the aircraft, maybe? :)

[Henry VIII]

Ditching and swimming procedures are in the QRH - Fuel leaks are notMay be not in your flying time, I do not know. Nowdays YES.For the Canadian A330 - It was not covered by their QRH (or SOPs).Sorry, but wrong again. Please, review Canadian accident history.

The Transat crew made wrong consideration assuming no possible leak and followed the "wrong" QRH path. If they whould have checked carefully the FOB+burn against the loaded one the "problem" would not have happened.
No engeneering manuals needed, simply follow QRH.it is all "by thebook" now and very little thought outside the box.This because statistics say that in modern aircraft there is a big percentage of accident due to application of "personally theory" derived from "too deep" knowledge of the acft sys.

[FE Hoppy]

Puddle on the ground - Vegas 97
Stream of fuel vapour from pylon - South Atlantic 95
Plume of fuel streaming from thrust reverser cascade vanes - North Atlantic 92

The last two were confirmed by un-accountable fuel imbalance. The first was confirmed by smell and touch.

[AeroTech]

Hi,

It will be nice if someone can post fuel leak procedure (Airbus, Boeing,...), if such procedure exists.

Thank you.
Regards

[Meikleour]

BelArg

I was current on the A330 at the time of that incident although not now - however, unless it has changed since, the QRH did indeed cover fuel leaks.
The problem was that the drill for a leak whose source could not be identified was for the crew to switch off the wing tank fuel pumps and see whether the engine flamed out! So you can imagine the crew`s feelings about doing this when way out over the ocean and at night. What has never been addressed however is, if the crew suspected malfunctioning computer readings, then why did they think it would be a `good idea` to open the fuel crossfeed. This action vastly increased the fuel loss rate yet they never seemed to pick up on that.

Your general sentiments about the `dumbing down` on technical knowledge is however shared by me also.

[One Outsider]

This because statistics say that in modern aircraft there is a big percentage of accident due to application of "personally theory" derived from "too deep" knowledge of the acft sys.

I assume you are able to back up that claim? Otherwise it could easily be dismissed as a "personal theory" made up for the occasion.

[wall-e]

FUEL CONFIG on the EICAS message maybe!

[Bruce Waddington]

BLY,

Most in flight leaks/imbalances will be caught when a 'Fuel Imblance' warning is presented or during routine checks. The outfit I worked for checked for balance and 'burn + onboard' fuel at least every hour.

Transport category aircraft will have a checklist for 'fuel imbalance' which will start out by asking you to add the fuel on board and the fuel used. If you get a sum very close to departure fuel you indeed have a fuel imbalance and would proceed with the checklist.

If there was a discrepancy the 'fuel imbalance' checklist will direct you to the 'fuel leak' checklist.

best regards,

Bruce Waddington

[AeroTech]

Hi,


Originally posted by Meikleour:
I was current on the A330 at the time of that incident although not now - however, unless it has changed since, the QRH did indeed cover fuel leaks.
The problem was that the drill for a leak whose source could not be identified was for the crew to switch off the wing tank fuel pumps and see whether the engine flamed out! So you can imagine the crew`s feelings about doing this when way out over the ocean and at night. What has never been addressed however is, if the crew suspected malfunctioning computer readings, then why did they think it would be a `good idea` to open the fuel crossfeed. This action vastly increased the fuel loss rate yet they never seemed to pick up on that.

I didn’t understand the phrase in bold. May be the reason to turn off the fuel boost pumps is to isolate a fuel leak upstream the fuel spar valve (fuel LP valve). I guess the engine will shutdown at cruise altitude with fuel boost pumps off. Fuel gravity supply (suction feed) will likely not be available until the aircraft will descend to a certain altitude. In my humble opinion if there is a fuel leak (upstream or downstream the spar valve) the engine will be shutdown and the crossfeed valve will be opened to supply fuel to other engine. All corrections are welcome.

It will be nice and helpful is someone can post the fuel leak procedure because it will shed some light regarding this matter (Airbus, Boeing,...). Some state that there is no fuel leak procedure: does it mean that such procedure was not available in old aircraft? May be added later after Air Transat incident???

Feedback appreciated
Thanks
Regards

[exeng]

Airbus changed the fuel leak QRH shortly after the Air Transat incident. I was on the A320 at the time and we were told the QRH was changed to reduce the risk of confusion as appeared to be in evidence in the A330 incident. It was years ago and I cannot now recall the details of the QRH change.


Regards
Exeng

[Bruce Waddington]

Here is the Airbus A330 procedure for FUEL IMBALANCE and for FUEL LEAK. (current as of May 2003)

FUEL IMBALANCE

FOB......................................................... ...............................................CHECK
Compare the FOB+FU with the FOB at departure. If the difference is significant, or if the FOB+FU decreases, suspect a fuel leak.

CAUTION

A fuel imbalance may indicate a fuel leak.

Do not apply this procedure, if a fuel leak is suspected. Refer to FUEL
LEAK procedure

– WING X FEED............................................ON

If the WING X FEED valve is open :
On the lighter side :
– (ALL) FUEL PUMPS (STBY then NORM)..................................OFF

When fuel balanced :
– PUMPS (NORM then STBY)...................................................ON
– WING X FEED ............................................................ ...... AUTO

If the WING X FEED valve is failed closed :
– OUTER TK XFR......................................................... .........ON
– BANK ANGLE ...............................3 DEG WING DOWN ON LIGHTER SIDE

Fuel transfer only occurs if the bank angle is at, or above, 2 to 3 degrees. Modulate
the fuel imbalance through the bank angle.
– RUDDER TRIM........................................................ .................USE
– Use rudder trim to get constant course and neutral stick.


Fuel Leak


A fuel leak may either be detected, if :

•
The sum of FOB and FU is significantly less than FOB at engine start, or is decreasing, or
•

A passenger observes a fuel spray from an engine/pylon or wing tip, or
•

The total fuel quantity is decreasing at an abnormal rate, or
•

A fuel imbalance is developing, or
•

Fuel quantity in a tank is decreasing too fast (leak from engine/pylon, or hole in a tank), or
•

A tank is overflowing (due to a pipe rupture in a tank), or
•

The Fuel flow is excessive (leak from engine), or
•

Fuel is smelt in the cabin.
If visibility permits, leak source may be identified by a visual check from the cabin.
LAND ASAP

LEAK FROM ENGINE/PYLON CONFIRMED :

Engine fuel leak can be confirmed by excessive fuel flow indication, or a visual check.

– THR LEVER (of affected engine) ........................................... IDLE
– ENG MASTER (of affected engine) ........................................ OFF
– FUEL X FEED ...........................................................U SE AS RQRD

If the leak stops, the crossfeed valves can now be opened to re-balance fuel quantity, or to enable use of fuel from both wings. Do not restart the engine.

LEAK FROM ENGINE/PYLON NOT CONFIRMED or LEAK NOT LOCATED

Stop any fuel transfer, and then monitor the depletion rate of each inner tank, to determine if the leak is from an engine or a wing (case 1), or from the Trim tank, or the APU/Trim feeding lines (case 2).

– FUEL X FEED ...................................................MAINTAIN CLOSED

The crossfeed valves must remain closed to prevent the leak from affecting both sides.

– T TANK FEED........................................................ ............. ISOL
– INNER TANKS FUEL QUANTITIES .................................. MONITOR

Monitor the depletion rate of each inner tank.
WHEN A LEAK IS CONFIRMED

CASE 1: IF ONE INNER TANK DEPLETES FASTER THAN THE OTHER
BY AT LEAST 500 KG (1100 LB) IN LESS THAN 30 MINS :
An engine leak may still be suspected. Therefore :

– THR LEVER (engine on leaking side)...................................... IDLE
– ENG MASTER (engine on leaking side).................................... OFF
– FUEL LEAK ............................................................ .... MONITOR

If leak stops :

If the inner tank fuel quantity of the affected side stops decreasing, the
engine leak is confirmed and stopped.
– T TANK FEED........................................................ ....... AUTO
– FUEL X FEED..................................................... USE AS REQRD

The crossfeed valves can now be opened to re-balance fuel quantity, or
to enable use of fuel from both wings. Do not restart the engine.

If leak continues (after engine shutdown) :

If the inner tank fuel quantity of the affected side continues to decrease, a leak from a wing may be suspected..

– ENGINE RESTART ..................................................... CONSIDER
– FUEL LOSS REDUCTION proc ...................................... CONSIDER

CASE 2: IF BOTH INNER TANKS DEPLETE AT A SIMILAR RATE :

A leak from the Trim tank, or the APU/Trim feeding lines may be suspected :
If fuel smell in the cabin :
– APU (if ON)......................................................... ............... OFF
– T TANK FEED........................................................ .MAINTAIN ISOL

This prevents additional fuel loss through the APU/Trim feeding lines.

If no fuel smell in the cabin :
A leak from the Trim tank may be suspected :
– FUEL LOSS REDUCTION proc .............................. CONSIDER

CAUTION
Do not apply the FUEL IMBALANCE procedure. Approach and landing can be one, even with one full wing/one empty wing.

FOR LANDING

CAUTION
Notify ATC and do not use reverse.

best regards,

Bruce Waddington

apologies for the formating

[Meikleour]

Bruce.

This contoversial checklist has `evolved` somewhat. The Air Transat incident was in Aug 2001.

Airbus QRH circa 1995 for A330

WHEN A LEAK IS CONFIRMED

* LEAK FROM ENGINE
Shut down the engine
* LEAK FROM WING TIP or LEAK NOT LOCALISED
Leak from wing surge tank may be due to fuel feed duct rupture leading to one tank overfilled.
- WING X FEED MAINTAIN CLOSED
- DESCENT TO GRAVITY CEILING
Refer to FUEL GRVTY PROC
- ALL TK PUMPS OFF


Ammended QRH circa 2004

WHEN A LEAK IS CONFIRMED LAND ASAP
* LEAK FROM ENGINR
This procedure must be applied, if it is positively identified that the leak is coming from the engine.
- THR LEVER (of affected engine) IDLE
-ENG MASTER (of affected engine) OFF
- FUEL X FEED AS REQD
The Xfeed valve can now be selected open for rebalancing or to allow use of the fuel from both wings. Do not restart the engine.

LEAK NOT FROM ENGINE or LEAK NOT LOCATED

- FUEL X FEED AUTO
The fuel crossfeed must remain closed to prevent the leak from affecting both sides. Selecting auto maintains the crossfeed valve closed.
- L and R INR TK SPLIT ON
L+R INR SPLIT ON splits the inner tank into two parts to minimise fuel loss in case of an engine rotor burst.
- T TANK MODE (if not empty) FWD
A manual trim transfer, must be done, to avoid automatic transfer to only the least full inner tank.
DESCEND TO GRAVITY FUEL FEEDING CEILING
Refer to Gravity Fuel feeding procedure.

When Trim Tank empty:
-T TANK MODE AUTO
-T TANK FEED ISOL
-ENG START SEL IGN

Flight conditions at the time of gravity feed ceiling:
- FUEL DEAERATED:(Flight time from take-off > 30 min), FL200
- FUEL NON-DEAERATED:(Flight time from take-off < 30 min), FL 150
- ALL TK PUMPS (when gravity ceiling reached) OFF
In almost all cases, switching the pumps off will prevent any further loss of fuel. All pumps must be switched off, even if the leak is from one wing only, as there are some failures on one side that will result in fuel loss from the other side.
-AVOID NEGATIVE G FACTOR

Caution: Do not open the FUEL XFEED even if requested by another ECAM procedure. Do not apply the FUEL IMBALANCE procedure. Even with one inner tank full/one inner tank empty, no special procedure is required for approach and landing.

* If one engine flames out when there is still fuel in the feeding tank:
- ALL TK PUMPS ON
-LEAK FROM ENGINE proc. APPLY
Note: The flame out is due to air suction from a leak from the engine.

So, as can be seen, this checklist is a bit `punchy` and not one I would relish tackling well away from suitable diversion airfield. The biggest mystery to me remains as to why the crew thought that opening the crossfeed was of any use to them. In fact if they had done NO checklists at all, the outcome would have been much more benign.
Judging from your checklist copy, Bruce, it would seem that it is up to the individual operators as to the amount of additional notes that are given to crews.

[skiingman]

When I was a young wiseass along for a ride on a 732, we were stuck at the gate due to a fuel leak from engine number one. Small amounts of fluid make big puddles, but this motor had a drip and a good size puddle below it regardless. Captain told us SLF that he was waiting on maintenance to come have a look. About an hour later, the desired maintenance staff hadn't turned up, but the captain had decided to start the engine under the theory that the leak would "seal itself". I thought that a little bit odd of a thing to do with an airliner full of people, but I was young and "wise" and the captain was certainly old and wise.

I got a rise out of some passengers (some laughing, some looking worried) by loudly inquiring what facts had changed that made it safer to just give it a shot an hour later with an even bigger puddle of fuel under the wing, and what exactly the plan was in case the leak decided to get worse. Uneventful flight of course, and I was a loudmouthed idiot, of course. One understands why flight crews choose not to tell the SLF anything of value...

[ampclamp]

If it was bad enough to delay the flt it was bad enough to wait for maintenance. Doing a start with a leaky engine with pax loaded , a puddle under said engine and I guess nobody outside on the headset to monitor for fire or to use an extinguisher if req'd was just a tad risky.
The one thing the old "wise" pilot did get right was many engine fuel leaks do heal up when seals are moved / pressurised etc. The rest was unacceptable risk imho.
Engine leaks/weeps, seeps are tolerated to given amounts by the AMM but should be assessed first.

[Henry VIII]

stuck at the gate due to a fuel leak from engine number one ... ... ... the captain had decided to start the engine ... ... ... an airliner full of people ... ... ... captain was certainly old and wise:eek: Wise...? :hmm: let's say a brave... to be polite :=I got a rise out of some passengers (some laughing, some looking worried) by loudly inquiring what ... ... ... what exactly the plan was in case the leak decided to get worsePax... :D

[muduckace]

I remember an MD-11 that drove us nuts, we were loosing/consuming fuel and could not figure it out. Climbing out at about 10k feet in this freighter someone went back during a ferry flight to have a smoke and noticed fuel streaming out of an overwing panel.

Just as soon as quantity dropped below the panel as far as required it would stop leaking and dry up well before landing.

[Bruce Waddington]

Meikleour,

You write, "The biggest mystery to me remains as to why the crew thought that opening the crossfeed was of any use to them. In fact if they had done NO checklists at all, the outcome would have been much more benign."

My understanding of the report is that the crew originally believed that they had a fuel imbalance and by memory tried to balance fuel. This of course involved opening the crossfeed.

Some time later they determined that they had a fuel leak, not a fuel imbalance. Unfortunately they never went back and closed the crossfeed, thereby creating a situation that allowed all of the fuel to be pumped overboard. Other issues that arose concerned the location of the leak and the need to shutdown an engine (which did not happen).

Leaving the crossfeed closed or shutting down the leaking engine would have stopped the leak and made the landing a powered one.

The report is a good read and there is lots to learn for all of us.

best regards,

Bruce Waddington

[Meikleour]

Hi Bruce

What does the report have to say about the crew`s conclusion that they had a fuel imbalance scenario without having done a FU + FOB comparison?

By the way I am quite surprised to see how different your operator`s QRH was from mine as listed. I thought that Airbus issued checklists to operators for them to reformat to their own requirements? I was with a launch customer for the A330 for 10 + years on type and saw many changes introduced by AI, but I have always thought that that checklist was `not for the faint hearted`!!

[Bruce Waddington]

M,

Try this link. It is not the full report but will give you the flavour of the issues. One of the key points is that the crew did not refer to the Fuel Imbalance Checklist and therefore did not note the caution at the beginning of the checklist:

FUEL IMBALANCE

"FOB......................................................... ..........CHECK

Compare the FOB+FU with the FOB at departure. If the difference is significant, or if the FOB+FU decreases, suspect a fuel leak.

CAUTION

A fuel imbalance may indicate a fuel leak.

Do not apply this procedure, if a fuel leak is suspected. Refer to FUEL LEAK procedure"


ASN Aircraft accident Airbus A330-243 C-GITS Terceira-Lajes AFB, Azores (LFB) (http://aviation-safety.net/database/record.php?id=20010824-1)

best regards,

Bruce Waddington

[Meikleour]

Bruce,

Thanks for the link. I followed the additional link to the Portugese Report and re-read it. Had read it many years before! It makes pretty damning reading! Page 58 of 103 confirms what I have been saying about the fuel leak checklist being a bit `punchy` - in fact the Air Transat captain himself admitted that he had not wanted to descend to the gravity ceiling.

I am still a bit puzzled as to why your posted checklist should have been so different from mine(Asian carrier) which was identical to the one provided to Air Transat as listed in the report. Did AC modify their Airbus checklists?

[Bruce Waddington]

M,

I don't know the answer to your question. Another possibility is that the checklist I posted was a revision after the Air Transat incident.

best regards,

Bruce Waddington