Gear Down In The Turn

[Mamakim]

Just wondering why putting the gear down in a turn is not good for it. It doesn't say anything in the POH about not putting the gear down in a turn but many people say don't do it but can't seem to give a good clear reason why.

Any suggestions?

MK

[RadioSaigon]

Interesting query! Never been suggested to me that it's 'not good' for anything and it is something I do -helps stabilise the speeds in the turn I find. Definitely interested in conflicting (or supporting) opinions!

What airframe specifically?

[Tinstaafl]

It's often thought that the likelyhood of a sideslip in a turn, or entering a turn, can lead to excessive lateral airloads on the gear & doors while in a transient state ie not locked up, and not locked down and gear doors open that would normally be closed at the completion of an extension or retraction cycle.

Whether that's the case or not is open to conjecture. I could argue that the pilot's skill should be such that unintentional sideslips don't occur, whether or not the unlocked gear system is sensitive. On the other hand, I've never seen a flight manual or POH that prohibits** extending the gear while turning or sideslipping. I've seen a few that caution against sideslipping for extended periods, but not for gear reasons.


**Slight correction due to a later comment below: The Aerostar's manual says it's not recommended, as best I recall. I don't *think* it says prohibited. Maybe it uses 'avoid' or similar language.. Haven't touched one in over 10 years. Perhaps someone with access to a POH would post the exact wording?

[RadioSaigon]

Interesting, thanks Tinstaafl -I'd certainly be interested in any qualitative studies or further information available if you know of any?

[ForkTailedDrKiller]

I was always told that it is not good form, for the reasons given above - ie lateral loading on the doors in transit.

I generally drop the gear before turning base and avoid cycling the gear in a turn - but if I need to then so be it. There is nothing in the POH to indicate that I shouldn't.

Dr :8

[43Inches]

It's the same theory as reducing limit speeds, by operating gear and flap say 10 kts less than the limit rather than taking it at the limit should reduce componant wear. Selecting gear during the turn is the same, side air loads and increased load factor will all place a greater strain on the doors, pumps and actuators.

[Joker 10]

Not if the turn is balanced, should be same as straight balanced flight, military operations pop the gear in the base turn.

[Tempo]

Spot on Joker 10.....

[tw682]

Guess all this would have the same issues as putting down flap in the turn??

[43Inches]

During the turn how is 1g maintained and therefore no increased load factor balanced or not.

The millitary reason for gear down turning base may differ slightly from civil reasons.

[Jenna Talia]

Just follow the POH. The Aerostar POH says not to do it, as it can rip the doors off.

I wouldn't worry about it if it is not in the POH. Just ensure the turn is balanced.

JT

[18-Wheeler]

Not if the turn is balanced, should be same as straight balanced flight, military operations pop the gear in the base turn.

I quite agree - And if I may add I always tried to put the gear down at the lowest reasonable speed I could, to save excess loading on the gear doors & mechanisms. Might have even saved a little fuel doing that as well.

[chimbu warrior]

My memory is not that good, but when I flew Barons for a PNG operator I am sure we had a note in our manuals prohibiting lowering the gear in a turn.

It wasn't in the manual on any of our other types, so I always assumed it was based on info from the manufacturer.:ok:

[desmotronic]

During the turn how is 1g maintained and therefore no increased load factor balanced or not.

...a descending turn.

[twista]

why would you be turning out of balance in the first place?

[Joker 10]

Dunno why you would turn out of balance and it is exceedingly difficult to "pull" excessive "G" in a desending turn at speeds that would allow gear extension.

In any event as long as everything is in balance the gear should extend without any side loads.

There is nothing that might stop flap extension in the same circumstances.

However if the AFM/POH prohibits either then it is not smart to ignore the prohibition.

Most higher performance military approaches are a continuous descending turn during which the airframe is made progressively "dirty" and slowed progressively to final approach speed, this is so good visibility of the circuit is maintained and the approach is tight and safe.

[Tmbstory]

If you are in balanced flight (should be) in the turn and the applicable aircraft manual does not limit it, then it would be okay.

In my time it was the side load issue that was the main reason for the caution.

Tmb

[Arm out the window]

Dunno about that, Joker 10 - what types are you talking about?
Gear is usually lowered on a straight downwind leg for most military types I know unless it's a spiral-type PFL.

[psycho joe]

Just wondering why putting the gear down in a turn is not good for it. It doesn't say anything in the POH about not putting the gear down in a turn but many people say don't do it but can't seem to give a good clear reason why.

Any suggestions?

MK


Quite simply.....Once upon a time at an airport not far away a lowy inexperienced grade 3 instructor who thought that they were an undiscovered test pilot came up with this "rule" and imparted their wisdom on a hapless student who didn't know any better, who(m) in turn became a low experience instructor armed with this superior knowledge who trained somebody, who became a CFI, who then made it law. :E


joe crazyhorse,

[FGD135]

Nothing to do with "side loads" in the turn - you get those in the straight and level too.

The only thing different about turning flight, from the point of view of the undercarriage, is the load factor.

If the undercarriage weighs 50 kg under straight and level 1g conditions, then it can weigh, for example, 60-70 kg in a turn.

If the POH prohibits it, that is because either:

1. The manufacturer believes that, over time, damage may occur to the airframe or undercarriage (due to the extra stresses incurred by extension/retraction during turns), or

2. Extension whilst turning was never trialled during certification flight tests.

This answer, by Martin.Sacklage illustrates the situation perfectly:
... we used to dump the gear when turning onto base under a higher than 1 G load as they were spring activated and this helped them to extend. Helps with issues in extending them.

psycho joe wins the prize for best explanation to why "many people say don't do it but can't seem to give a good clear reason why."

[GABLUES]

Oh how true, the newby with all his or her new idea's and unsupported theory,that surely must be a better way than the decades of experience passed off as what would that old git know...:)

[Mach E Avelli]

The restriction on selecting flap in a turn (usually only a recommendation, but some instructors train that way) may be valid for aeroplanes that don't have asymmetry protection for the obvious reason that a surprise asymmetry could make life temporarily miserable if it happened in a turn. As has been mentioned, a descending turn won't impose 'g' loadings likely to cause any problems with either the gear or flaps. If the turn is balanced there won't be side loads, so the gear thingy must be unique to a few types, none of which I have flown.
If the POH or AFM says don't activate the gear or flaps in a turn then that is a clear limitation - period. If some other WRITTEN instruction from the owner or operator wishes to add additional limitations, it is incumbent upon the pilot hiring or being paid to fly the aeroplane to obey those instructions - whether they have any real basis or not.
But if it's just some silly old tosser's pet theory, ignore it if you know better and are certain that no instructions to the contrary exist.

[tio540]

Gear down and locked, complete checks/checklist, then base turn.

Completing the checks/checklist on base keeps your eyes in the cockpit when you should be looking out. Fair enough too.

Aerostar gear door's do bust in turns if uncoordinated. Fortunately wasn't me.

[LeadSled]

Folks,

military operations pop the gear in the base turn.,


Or popping the gear inverted, in an (over) enthusiastic pitch and break.

Quite frankly, with the ball in the middle (and we all keep the ball in the middle, don't we, kiddies) it doesn't matter when you put the gear down, from the machinery's point, and a little "G" can assist, as I once found out when I had a main gear hang up --- took about 2.5 G to pull it out --- then needed a good sideslip to get it to lock (an old 707 trick)

No names, no pack drill, but there is one aircraft where a particular common nose gear problem only responds to a serious pullup, say 5G (it's limit is 7.5)

Tootle pip!!

FGD135 ---
Fer gaaarrds sake, what kind of angle of bank are you using in turns in the circuit.

And what kind of loads do you think the gear linkages take in normal taxying around a paddock, or some of the lousy sealed surfaces we operate off.

Psycho's the man with the answer.

[werbil]

Gear down and locked, complete checks/checklist, then base turn.

Completing the checks/checklist on base keeps your eyes in the cockpit when you should be looking out.


The 'preferred' method of joining a circuit according to the powers that be is an oblique downwind - right where you suggest pilots should be configuring for landing and doing checks - eyes inside where inbound and circuit traffic are converging - eyes outside when following other traffic.

[tio540]

The 'preferred' method of joining a circuit according to the powers that be is an oblique downwind

At different altitudes for light aircraft to boot.:bored:

[Joker 10]

Or upwind for a pitch and break.

[FGD135]

LeadSled, how about you read my post properly?

Fer gaaarrds sake, what kind of angle of bank are you using in turns in the circuit.I made no references at all to turns in the circuit. The thread was about putting the gear down in a turn (read the title of the thread) and that was the issue I was addressing. RTFP.

And what kind of loads do you think the gear linkages take in normal taxying around a paddock, or some of the lousy sealed surfaces we operate off.Wasn't addressing that aspect. Do you think I'm advocating not extending the gear in the turn? You need to read my post again. My post was purely about answering the question put by the original poster. RTFP. I was not suggesting it should or should not be done - and I was not comparing the loads to those at other phases of flight. RTFP.

I question your ability to comprehend simple posts, LeadSled. You have read two things into my post that I clearly hadn't written. Please read the posts a bit more slowly and carefully next time. You have wasted our time.

[sockedunnecessarily]

I'm quite surprised the other military or ex-military pilots on here who have commented don't know the real background behind this reasoning.

There was a single pilot military aircraft many moons ago (I can't for the life of me remember the aicraft type) where the location of the gear lever caused a head turning movement as the pilot leaned over and looked for it and then lifted the head back up (the selector may have been on the floor, not sure...). This head twisting and leaning while the aircraft was turning was causing extreme disorientation and aircraft at night were rolling over on their back during the base turn.
I think it is called a Coriolis illusion but can't be sure, and remember it being demonstrated to me on a spinning chair. It is not like most illusions - it is a particularly violent, uncomfortable and sudden feeling.

The fix was to mandate gear extension during level, unaccelerated flight. Problem solved.

Today, where ergonomics play a much larger role in aircraft design this problem has hopefully been eliminated. The gear lever is generally installed in a location which requires minimal head movement, and multi crew also removes the issue as the handling pilot is not operating gear/flaps etc.

Moral of the story is... If your AFM says you can't do it in your aircraft type, don't do it. If you are single pilot at night, minimise head twisting/turning/lifting movements and consider gear extension in level flight to prevent coriolis illusion. It is nothing like the leans or somatogravic... just feels like your head has been hit by a bus.

[Tee Emm]

Quite simply.....Once upon a time at an airport not far away a lowy inexperienced grade 3 instructor who thought that they were an undiscovered test pilot came up with this "rule" and imparted their wisdom on a hapless student who didn't know any better, who(m) in turn became a low experience instructor armed with this superior knowledge who trained somebody, who became a CFI, who then made it law.

Probably the same instructor who advocated reducing the rpm to minimum on both engines before selecting gear down at max limit gear speed, because the slipstream over the gear doors caused by the propellers at cruise RPM would increase the local airflow over the landing gear doors so much that the faster airstream would mean the dynamic pressure would exceed the max gear down IAS and risk damaging the gear mechanism:ok:

[Bullethead]

The Blue Angels put their gear down in a turn - a vertical one! :}

[Joker 10]

And inverted at that, ball in the middle, check gear speed, extend. No big deal.

[Bullethead]

So Joker 10 if they extend the gear while inverted then that would be "Gear Up!" wouldn't it? :}

[PyroTek]

Bullethead: "Gear extended and locked" fixes that :p