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A320 Hydraulic Trouble?
Posted: Sat Jul 22, 2006 2:21 pm
I flew with Aer Lingus from Faro to Cork on Tuesday the 18th of July. I am no expert but this is what I saw and heard.
When I was boarding the plane I saw a large puddle around the right main gear. I didn't think much of it because it had baan raining earlier that day.
On start up I heard a noise coming from under my feet that sounded like a dog barking. I was sitting just behind the wing on row 17. I was a bit concerned but thought nothing of it.
When the flaps were extended for takeoff the noise started again. A few people in front of me were also getting worried. After takeoff when the gear was retracted the noise was very loud. This noise occured every time the flaps were extended or retracted throughout the climb and descent.
On finals the gear was dropped. It was obvious that there was a problem. The gear took a long time to drop with the sound like a dog barking. It took much longer than usual to lock into position.
We landed at Cork at around 11.30pm. As soon as the engines were shut down a swarm of engineers came and opened two large doors next to the main gear.
Did this aircraft have serious hydraulic problems and should the captain have taken off even though there were many signs that all was not well?
Re: A320 Hydraulic Trouble?
Posted: Sat Jul 22, 2006 3:50 pm
[quote="airoshane"]...............On start up I heard a noise coming from under my feet that sounded like a dog barking. I was sitting just behind the wing on row 17. ..............
do you know if there was a dog in the baggage hold ?, could be just a coincidence that you actually did hear a dog barking at the time the engines were started. animals put in the baggage hold are mildly sedated and still awake.
[quote]When the flaps were extended for takeoff the noise started again. ....................... After takeoff when the gear was retracted the noise was very loud. This noise occured every time the flaps were extended or retracted throughout the climb and descent.
[quote]We landed at Cork at around 11.30pm. As soon as the engines were shut down a swarm of engineers came and opened two large doors next to the main gear.[quote]
were these doors on the fuselage? are you not mistaking them for the baggage hold doors which are large doors on the right hand side of the aircraft either side of the wing?
maybe you mistook the baggage handlers for engineers?
it may be because you were sitting behind the wing that the noise of the flaps retracting and landing gear lowering sounded louder than say if you were sitting up the front of the aircraft.
Posted: Sat Jul 22, 2006 10:13 pm
It was definately a mechanical sound. A friend of mine told me that when hydraulic fluid passes from one system to another it makes a noise like that. He said it's common on start up but should have stopped once both engines were fired up. The fact that it was happening throughout the takeoff and landing means there was a problem... According to him.
I fly on commercial aircraft a lot and sit over the wing on most of them. I know what all the noises are and what they should sound like.
The doors were definately for the gear. they were under the fuselage between the main gear itself. I have a pic of the doors but its a bit blurry because it was dark when I took it.
I m really interested in finding out exactly went wrong. Perhaps another member of this forum may have been on board.
Posted: Sun Jul 23, 2006 5:27 pm
All the events you describe are a normal part of a A320 flight if you are sitting over the wing.
The fluid on the ground is either excess water from the air conditioning packs in high humidity or warm temps or water from the galley drains.
The noise like a dog is the hydraulic power transfer unit.
The engineers under the undercarriage do this every night for the last flight as they lower the undercarriage doors, their eagerness is explained by their desire to go home.
Relax, it was supposed to be a holiday
Posted: Sun Jul 23, 2006 8:54 pm
Correct, on engine start up one of the engine driven hyd systems can power the other through the power transfer unit or PTU. It protects the hyd in the event of an engine failure i.e. you can run the two main engine driven systems on just one engine via this link. it does make a bit of a racket on start up but it's normal. The 330 and 340 dont have this, instead they have a dedicated electric pump on each of the 3 hyd systems, so not as noisey. The swarm of engineers is down to a daily check which has to be done every 24hrs and for this the main gear doors have to be opened. Sorry to tell you you were never in any danger!
Posted: Mon Jul 24, 2006 12:46 am
the engineers swarm over,well 2 at most in cork to get the ramp 1 check done and get out and go home unless theres scheduled maintenance or a snag,the handiest thing to do for them is to open the landing gear doors first as something to do while your waitng for pax,crew and baggage handlers to clear out of the way.
Posted: Mon Oct 09, 2006 5:53 pm
Firstly i don't think the "puddle" you saw around the main gear was was hydraulic fluid if you could have easily confused it with rain, hydraulic fluid mainly used in aviation is either red, purple or green. Where you were sitting on the aircraft give or take a few foot would have been directly over the hydraulic reservoir which feed the whole system, so there is bound to be a few noises associated with its operation.
Here is my theory. There is such things as hydraulic accumulators in aircraft, they consist of a gas side and a liquid side(hydraulic fluid) usually seperated by a piston. The gas side is charged with a programmed pressure usually with nitrogen, and the purpose of all this is to store hydraulic fluid at pressure, redundancy if the pump fails, provide the initial pressure when the pilot makes a selection, and also to decrease the wear on the pump by maximising the time between cut-out and cut-in of the automatic cut out valve. If for some reason(there are many) the predetermined pressure in the accumulator is not being achieved the automatic cut out valve will cut in and out more often than normal which wears the pump out and causes very fast fluctuations of system pressure. This can be heard and felt (from your seat) as very light beating(not a dog barking) when a selection is made in the cockpit.
This is not a major problem and can be sorted out fairly easily, not something you would stay on the ground in Faro for anyway. That is of course if this was the problem.
Posted: Mon Oct 09, 2006 8:24 pm
The Sound is the PTU and is very similiar to that of a dog bark and somewhat loud when sitting mid cabin.
The puddles around the gear or just inboard of the gear under the wing is pretty much always due to moisture dripping off the struts or wing underside when pulling on stand after a flight which will create a little puddle and from time to time does get noticed by some eagle eyed pax.
Posted: Wed Oct 11, 2006 12:21 pm
I still don't think its normal for the PTU to be barking throughout the takeoff and landing phase. Its normal on pushback and single engine ops but we definately had 2 engines for takeoff!
Posted: Wed Oct 11, 2006 6:21 pm
Just in passing,
I flew Eirjet Shannon-Lanzarote and back.
On the return leg on EI-DKG (Air Jamaica c/s) just after push there was a loud noise from under the front of the aircraft, I cant really describe it. Like EEEEEEEEEEEEEoooooooooooooooooooooerrrrrrrrrrrrr. I have never heard it before, and I never heard it on the flight from Shannon. Was it to do with the cargo doors?
It was not flaps or anything. They were already left extended after landing.
Posted: Thu Oct 12, 2006 7:25 pm
Rallye EI-BFP wrote:It was not flaps or anything. They were already left extended after landing.
I don't think so
On the A320 flaps are always retracted on leaving the runway after landing and set just after engine start after push back.
Posted: Fri Oct 13, 2006 6:17 pm
Well I do think so
I have seen it happen a few times
Posted: Sat Oct 14, 2006 12:29 am
Would be very strange for an aircraft to pull into the gate with flaps extended.
A320 after landing checklist:
ENG MODE SEL...............NORM
I have however heard one reason for leaving them extended, that is if you land at an airport where the weather is freezing and the runway is contaminated with slush or snow it can be a good idea to leave them extended. The reason behind this is that during the landing roll slush and snow can be thrown up by the tyres on to the flap housings and tracks. If this freezes you can damage the flaps by retracting them. An inspection by ground personnel is recommended before retracting them.
AHH... not much snow or freezing weather down in the canaries though. We should rename the thread A320 Strange Noises.
Posted: Sat Oct 14, 2006 9:46 am
As it has been alluded to in previous posts the noises you heard during pushback are perfectly normal and are the hydraulic system pumps pressurising the system and the hydraulic PTU performing a test sequence after the NO.2 engine has started and during engine NO. 1 start.
As to leaving the flaps down after landing 5 possiblle reasons :
1. Not for discussion on a public forum
2. Landing during Icing conditions and need for inspection
3. Landing at Airport where temp 30 Degrees or greater leaving flaps down reduces the possibility of Pylon Over Heat
4. Flap Fault
5. The pilots just forgot !!!!
Hope this answers your question and reassures you...
Posted: Sat Oct 14, 2006 12:06 pm
Temperature was at least 30 degrees, or pilots forgot!
I think it is a 'time saving' (well, saving what, 10 seconds!)
Larger aircraft I have travelled on the crew tend to have this habit.