Undercarriage refuses to retract on CX715 Monday 24/05/2010

[anat0l]

I'm not sure which forum this should be in - Trip Reports, Your Questions...Playground?

Anyway, this is both kind of a report as well as a bit of discussion on the issue. It's a first hand account as a passenger (I was there), but I wouldn't start selling this to any sensationalist media outlets (although.... *thinks money* )

The date is Monday 24/05/2010 and the flight is CX715 HKG-SIN, operated by a CX A330-300 with regional configuration, rego B-HLF. Fairly full-ish flight, as most HKG-SIN services are. STD was 2000h and we left on time; est flying time was 3h 45min with an ETA in SIN of 2345h.

We take off, no big dramas. I noticed things started to get a bit funny when the emergency exit signs (the illuminated "EXIT" signs) weren't being turned off (either that or they were turned off and then turned back on) during our ascent. At that point I didn't hear anything unusual and we continued our ascent into level flight - my aviation terminology is extremely poor, but we levelled out not at a cruising level above the cloud layer but rather at a level where you can see all of the ground etc. below the cloud layer. It's that level where you've just punched through the cloud layer and about to land. Sorry for the poor description - someone help me out here....

Anyway, I was surprised we weren't going any higher. I thought I was being paranoid, so I laid back and relaxed. During this whole time, the seat belt sign did not turn off. It took about another 15 minutes before our captain came onto the PA to announce that there was a fault with the aircraft. The undercarriage had failed to retract so the wheels were still sticking out and presumably this meant that if you were sitting in a seat close to where the undercarriage is, there was quite a significant racket to be put up with. Within the next 30 minutes, the captain had come onto the PA to announce the following recovery procedures:

• There was no safety concerns, the plane is still in a serviceable condition.
• The plane would be turning back to HKG (not continuing onto SIN). A backup aircraft (also an A330, arriving from another sector) would be waiting for us when we got back to HKG.
• Due to the weight of the plane and landing requirements, we would have to spend some time in the air going around in circles burning fuel. This would give us an ETA back to HKG of about 2200h.

At the announcement of the final point, about 3 pax in J got up and vented their anger at the flight attendants. Their main argument was, of course, why couldn't the plane simply continue onto SIN given that we had to spend at least 1 hr in the air burning up fuel anyway. I don't know what the FAs said to hold them at bay, but they did go back to their seats.

The seat belt sign was still on for a significant portion of the flight, but that didn't stop people from getting up to use the toilet, nor did it stop them from using laptops and other electronic devices. (To be fair, this was not well advised nor well controlled by the crew).

Refreshments were served (drinks, nuts and - selectively - garlic bread) - no meals. Quite a bit of rising up and down by the aircraft during the whole time that we were up in the air burning off fuel to get the weight right.

We landed back in HKG as promised at 2200h. Eligible pax were invited to use the CX Pier lounge (as per their normal entitlements); Y pax were supplied with refreshments of soft drinks, water and a sandwich roll at our new gate.

I called notzac when I got back into the terminal; we had met earlier in the day and I'd expected that we wouldn't meet again due to timing of our flights, but, as they say, it's funny how things turn out. We shared more conversation and I had some food and a pot of tea from the Pier lounge, but it wasn't long before boarding was called again for the new CX715, now being operated by B-HLC.

Some funny observations for the new flight, or "round two":

• There were no pre-flight drinks
• Someone forgot to put on the safety demo (yes we had seen it during "round one", but still surprised it was not screened again)
• Pre-take off checks were kinda lax-ish. In some cases, we were well into taxi before FAs insisted on some pax turning off their laptops (is a laptop in sleep mode considered good enough as "turned off"?)
• There were no menus distributed - we were told our options for main courses as they came with the trolley. I think special meals were able to be accommodated for (there was one pax in the row in front of me that seemed to get his special vegetarian meal). Other than that, standard dinner service was offered, with full appetiser, main and dessert.
• No other compensation was offered

We eventually landed in SIN "on time" (with a noticeably very, very tired passenger contingent) at 0245h (25/05/2010).

There was always a lot of speculation, frustration and discussion about why we couldn't have just flown to SIN even with the wheels out the whole way. Not that I was concerned for the time (although for the suits with last minute
presentations etc., could understand why they were frustrated at not getting to their hotel rooms earlier and getting some decent sleep).

So there you have it. That was the first time I've been on a flight that has had to be turned back to the origin. I won't say I hope you liked the TR, but more there are some points of discussion to be had (and possibly some pilot expertise, of the likes of say jb747, might be desirable here):

• Barring that we don't know much else about the condition of the other elements of the aircraft, why couldn't have we just flown onto SIN and the problem addressed there? Especially since we had to be in the air anyway due to the need to burn fuel?
• Why couldn't we have landed in HKG with the load we had? I'm guessing that in order to safely land (with a comfortable speed and in order to not overshoot the runway), we had to reduce the weight (and thus inertia) of the aircraft, primarily by reducing the amount of carried fuel.
• Are there special procedures/flying patterns adopted when burning fuel simply to use it up for a landing, as in this case? I wonder how much fuel was actually burned in the hour we needed to get the weight down.
• Why couldn't they have just dumped fuel to save time? I'm assuming this is because (a) it wasn't deadly urgent to lighten the load and land, and (b) it's not environmentally friendly to do so
• Was the pilot right in reassuring everyone that there wasn't a safety issue? Again, must bar the fact that we know nothing else about the condition of the aircraft

 

[markis10]

So there you have it. That was the first time I've been on a flight that has had to be turned back to the origin. I won't say I hope you liked the TR, but more there are some points of discussion to be had (and possibly some pilot expertise, of the likes of say jb747, might be desirable here):

• Barring that we don't know much else about the condition of the other elements of the aircraft, why couldn't have we just flown onto SIN and the problem addressed there? Especially since we had to be in the air anyway due to the need to burn fuel?
• Why couldn't we have landed in HKG with the load we had? I'm guessing that in order to safely land (with a comfortable speed and in order to not overshoot the runway), we had to reduce the weight (and thus inertia) of the aircraft, primarily by reducing the amount of carried fuel.
• Are there special procedures/flying patterns adopted when burning fuel simply to use it up for a landing, as in this case? I wonder how much fuel was actually burned in the hour we needed to get the weight down.
• Why couldn't they have just dumped fuel to save time? I'm assuming this is because (a) it wasn't deadly urgent to lighten the load and land, and (b) it's not environmentally friendly to do so
• Was the pilot right in reassuring everyone that there wasn't a safety issue? Again, must bar the fact that we know nothing else about the condition of the aircraft

A couple of answers for you:

The service height of an aircraft that is unclean is lower than the normal ceiling and an aircraft is also very uneconomical in that sort of operation with the extra drag, the other issue a failure to retract could be a symptom of a bigger problem, why leave home base with a problem that you dont know the extent of or the cause?

In the case of the A330 with the gear not retracted company limitations include:
— The maximum altitude is 35,000 FT.
— Do not fly into expected icing conditions
— Ditching with landing gear down has not been demonstrated.
— Do not use managed speed (except in approach), and CLB and DES autopilot modes.
— Disregard FM fuel predictions. Other predictions should also be disregarded (altitude, speed and time), except time predictions at waypoints when in cruise.

Generally that aircraft is limited to 21000ft in reality for a variety of reasons.



As for the need to burn fuel, many aircraft take off with an aircraft that far exceeds the permissible landing weight, which is the maximum load an aircraft is designed to handle in terms of stresses on the equipment on a regular basis, the A330-300 can land at MTOW but it requires an inspection afterwards. A330-300's generally dont have a fuel dump option as they dont have a centre tank AFAIK while the A340 does, its very slow: 1000kg per minute (1600kg/min on the -600), from memory max fuel is 109T.

 

[Flying Fox]

I must say that I enjoyed your report and I have also never been on a flight that has return to origin. The closest that I have been is a flight that has pushed back and about to disconnect from the tug and then was pull back to the gate.

As for flying with gear down, I asked the same thing about a flight ADL-MEL. As stated previously I believe that its a fuel burn and risk issue. Afterall, the safest place for a plane is on the ground ASAP.

 

[serfty]

...

1. Barring that we don't know much else about the condition of the other elements of the aircraft, why couldn't have we just flown onto SIN and the problem addressed there? Especially since we had to be in the air anyway due to the need to burn fuel?
2. Why couldn't we have landed in HKG with the load we had? I'm guessing that in order to safely land (with a comfortable speed and in order to not overshoot the runway), we had to reduce the weight (and thus inertia) of the aircraft, primarily by reducing the amount of carried fuel.
3. Are there special procedures/flying patterns adopted when burning fuel simply to use it up for a landing, as in this case? I wonder how much fuel was actually burned in the hour we needed to get the weight down.
4. Why couldn't they have just dumped fuel to save time? I'm assuming this is because (a) it wasn't deadly urgent to lighten the load and land, and (b) it's not environmentally friendly to do so
5. Was the pilot right in reassuring everyone that there wasn't a safety issue? Again, must bar the fact that we know nothing else about the condition of the aircraft

Aside from markis10's accurate comments, I make the following:

1. The aircraft would be severely speed limited without the undercarriage retracted. The Maximum speed with undercarriage extended (VLE) being 250kt¹ is substantially less than normal cruise. HKG-SIN is 1380nm as the crow flies so you automatically have a 5½+ flight should that be attempted.
2. The maximum landing weight of a 330 is something over 180 tonne¹, presumably the aircraft take-off weight was over this. Aircraft can be landed above the recommend weights but special procedures need to be followed which can put the aircraft out of service for weeks if not months.
3. Additional fuel can be burnt by flying at low levels with flaps, undercarriage (!) extended.
4. I believe Cathay have a policy against dump of fuel except in a emergency where landing shortly after take-off is necessary :

   Fuel jettisons (or fuel dumps) refer to the release of fuel whilst airborne when there is an urgent need to reduce the weight of the aircraft to the maximum landing weight. The dumping of aviation fuel is an extremely rare event. It affects a small number of long-haul flights only when unscheduled landings are required shortly after take-off or due to a diversion to an alternative airport in the event of an inflight emergency.

5. Almost certainly. The aircrew would have been very sure of the situation and have calculated how long to fly at the high fuel burning configuration in order to get the aircraft weight down.

¹ http://www.a330jam.com/documents/limits.pdf
² http://downloads.cathaypacific.com/cx/press/SDreport_en2009.pdf#page=23

 

[MEL_Traveller]

We take off, no big dramas. I noticed things started to get a bit funny when the emergency exit signs (the illuminated "EXIT" signs) weren't being turned off (either that or they were turned off and then turned back on) during our ascent.

Thanks for the report!

Just for those that aren't aware - airbus aircraft exit signs turn off when the undercarriage is retracted after takeoff, and illuminate again once the undercarriage is fully extended for landing.

What I haven't been able to determine (even after talking with friends who are cabin crew) if whether the illuminated sign actually means the exit is useable at that point? Perhaps markis10 you know the answer? (I'm thinking mainly about cabin pressurisation - does it mean, until the light is extinguished, and from the time it is illuminated again, that cabin pressure is sufficiently low to allow the opening of the exit?)