Aileron Trim on 767

[Corsairoz]

Firstly I am SLF, with a PPL, no real knowledge of anything beyond that. I do travel a lot on business and I'll try to be humble.

Last week I was in a BA 767 on a short haul in Europe. Sitting in 29K just aft of the wing. I noticed in the straight cruise that the starboard inboard aileron was deflecting in normal straight flight. Perhaps 8-10 cm of permanent down. Since I had never seen this before I was 'intrigued'. I even got up and wandered over the other side to see the port aileron with the same level of up deflection. So, a permanent right aileron trim in the cruise. I was so intrigued I got my bag out from the overhead and took a pic. I can post it if its of interest.

So, my questions:
How normal was this occurence?
Presumably the a/c was effectively crabbing along in the cruise, would this be affecting fuel and control?
After the flight into heathrow I humbly stuck my head into the flight deck and the Captain and 1st Officer seemed interested and wanted to see the pic and even said that they were going to call the engineers to tell them. Where they just being polite?
How welcome is this type of SLF comment on the flight decks? If I see something odd next time, should I tell or is it better to keep quiet.?In 25+ years of flying its the only odd thing I have spotted, so its unlikely to happen again. But I did have a shall I?/shan't I? moment before deciding to tell the crew.

Obviously all was safe.

Cheers
Trevor

[SMOC]

The SOPs of the airline I fly for is to select HDG HOLD once in the cruise and use rudder trim to trim the control wheel to neutral or near to, and therefore have the ailerons virtually neutral.

If it takes a significant amount of rudder to do so we would raise a tech log entry, which would probably result in a rigging check.

The crew of your flight may have mentioned it to the engineers or made a tech log entry which may or may not have resulted in a rigging check.

[stilton]

Why is there such a fascination with applying nautical terms to Aviation :confused:

I'm as big a nautical fan as any but in nearly 30 years as a professional Pilot i've never seen the terms 'Port and Starboard in any official aviation publication.


What am I missing....?

[Bullethead]

Well done Corsairoz,

I've had the occasional pax comment along those lines about things various over the years and I'm always ready to meet and chat with the person involved. Found a bolt missing on the LE Slats once and in your case it sounds like a slight case of misrigging, which usually can be easily remedied, and wouldn't have been noticed on the flight deck.

I spoke with a pax recently about what he thought was an abnormality he noticed when the flaps extended. I spoke to the engineer and we extended the flaps during the turn around and indeed there was a fairing coming adrift, which was then rectified. I had business card from the aforementioned pax so I rang him and thanked him for the information. He sounded chuffed that I took the time.

Even if there was nothing untoward chatting with the pax and maybe setting their mind at ease is worthwhile PR.

Regards,
BH.

[Piper19]

:ok:you can be sure a mechanic has looked to that occurance. I've had it several times in my carreer, most of the time it was a misrigging as said, but we also got a spoiler that didn't retract 100% on 1 side, and we even got an old aircraft with a slightly twisted fuselage (hard landing?). That a/c flew many years with aileron trim just within limits. I don't know if that would be tolerated nowadays...

now a question, with the deflection you mention, would a 767 pilot be able to see it if the autopilot gives a continuous aileron input of that kind? As I recall the only clue the pilot has is a sticker on the steering wheel with trim units on it.

[Bullethead]

G'day Piper19,

Apart from the sticker on the control wheel, which you would hope is in the correct position, you can call up the EICAS Status page and have a look at the control positions.

Several things could cause the condition, a mismatch in thrust, flight control misrigging, imbalance in fuel tank quantity or as has been mentioned a slighty bent aeroplane.

Regards,
BH.

[Corsairoz]

Since it seems I did the right thing...here is the pic. Sorry for the bad quality , its a still from a video camera.

This is the view I got for 2 1/2 hours in the level cruise.

http://i170.photobucket.com/albums/u249/corsairoz/DSC00001.jpg

[Piper19]

that's indeed a lot of steering input to stay level!

[tightcircuit]

Just out of interest,

The 767 has outboard and inboard ailerons. At higher airspeeds the outboard ailerons are locked out to reduce airframe stresses. This leaves just the inboard ailerons for small levels of roll control (If more roll control is required at higher airspeeds then the spoilers also come in to play at a certain control wheel displacement).

As stated above we would normally trim the a/c so that the ailerons were neutral. If this were not done then since the inboard ailerons are small and do not have a large lever arm (ie they are close in to the fuselage) then a significant displacement is required to correct small imbalances. A small amount of rudder trim allow them to return to neutral.

TC

[glhcarl]

No matter how hard the manfacture tries sometime the wings (or vertical stabilizer) are not installed exactly right. So the aircraft may require a small amount of trim to fly stright and level.

To accomplish this during a test flight the aircraft is trimed to fly stright and level and the required amount of trim rerquired is noted. After landing, the recorded amount of required trim is put into the system. The trim unit is then removed and reclocked to zero.

This is call "trim bias", even though the trim wheel reads zero there is a small amount of trim always there and the aircraft flys stright and level.

[singpilot]

Reminds me of a pic taken from behind the wing of a 747 in cruise. 13 hours of slightly extended spoilers right next to downward deflected inner aileron. Opposite wing was flush and clean.

The thread on that one ran several months.

[oceancrosser]

Why is there such a fascination with applying nautical terms to Aviation

I'm as big a nautical fan as any but in nearly 30 years as a professional Pilot i've never seen the terms 'Port and Starboard in any official aviation publication.


What am I missing....?

I think it´s a British thing...one of the last remnants of the Empire. I flew the Fokker F27 :ugh: and it was full of Port / Stbd references...awful airplane.

Now back to the thread itself, this appears to be indicative of a badly out of rigging airplane. Expensive.

[the rim]

agree with most ...bent airframe miss rigged controls and the like but when i get a defect that the aircraft is not flying as it used to i always ask is the airleron trim in netural as sometimes they have not adjusted the ail trim ....as to the use of port/stbd we use it all the time in aussie and i have been around for a bit