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Full-flap ferry with a TB-20?

“How is this accomplished?”

The previous guy deployed them at 150kts where VFE is 100kts? If they are stuck after that then there is a good reason…

Paris/Essex, France/UK, United Kingdom
Ibra wrote:

VNE landing?

How is this accomplished?

Ah, okay, so we’re talking about a flap overspeed (Vfe), rather than attempting to land and aircraft at Vne!

A lot of things in piloting require dedication to precision. Recognition of limitations, and correct interpretation, expression, and adherence are vital!

Though flap overspeeds are very unwise, and should never be done deliberately, a small flap overspeed is not critical as long as it not associated with turbulence, or pulling G.

Home runway, in central Ontario, Canada, Canada

Pilot_DAR wrote:

It’s bee a while since I flew a PA-28, but my recollection is that, like a manual flap Cessna, when the mechanical lever in the cockpit us up, the flaps are extended. When they are extended, it’s ideal that they remain that way, as the pilot desires, so “stuck” is likely a good thing. When the pilot wishes to retract the flaps, they push the position lock button at the end of the flap lever, and reposition the flaps as desired. If the flap position will change without the pilot pressing the lock button, or moving the lever, or, particularly with an application of power, the plane is very certainly NOT airworthy! Electric flap systems are entirely different.

The PA-28 flaps are not locked downwards when extended.

ESKC (Uppsala/Sundbro), Sweden

Some singles are restricted from take-off with full flaps by POH limitation. I have not checked the TB-20, but some of you would probably have mentioned it in case.
Also, most POH recovery procedures from stalls and especially incipient spins includes a retraction of the flaps, which probably is to protect them from Vfe overspeed and flaps-down g-limits rather than a controllability issue, but still, a procedure that cannot be performed with inop flaps. Then is the airplane airworthy?

(Yes, PA-28 flaps sometimes get stuck in the extended position and may come up with a bang sometime after moving the lever to the retracted position, e.g. during runup, but that is definitely another matter, as those flaps systems are very different from the TB-20.)

huv
EKRK, Denmark

Airborne_Again wrote:

The PA-28 flaps are not locked downwards when extended

That makes it sound as though one or both flaps could retract uncommanded. That would not be airworthy!

huv wrote:

Yes, PA-28 flaps sometimes get stuck in the extended position and may come up with a bang sometime after moving the lever to the retracted position, e.g. during runup

I only have a few hundred hours in PA-28’s over the decades, but have never experienced this, but I read through the POH, and note that it does say that they are spring loaded to return to the up position. I guess that I’ve always been lucky to fly a PA-28 which has been operating correctly! I would certainly hope that pilots were not attempting to blow a recalcitrant flap to the up position with full power on the brakes! What a horrible situation for the prop!

Home runway, in central Ontario, Canada, Canada

My vague recollection (~40hrs on a PA28-161 and another ~40 on PA28-181) from pre-2002 is that the flaps are indeed spring loaded but in the sense that you can push them down if you step on them (e.g. accidentally). You cannot push (or, more accurately, pull) them up otherwise, obviously, the airflow would just push them up and they would be a waste of time.

So yes they are spring-loaded to return to a position above the current position – once the lever has been moved to release them. If airborne, the spring would be superfluous, but it is required on the ground.

I can imagine that if a PA28 flap mechanism is well buggered / seized / full of muck then the spring won’t be able to raise it, so this would be where the high engine power stunt would come from. Staggering anybody would fly a plane in such a condition, but most of us have seen much worse

The TB20, BTW, has a tube and a UJ joining the two flaps, so assymetric flaps can’t happen unless something is dramatically wrong. But it has happened.

I don’t know the circumstances of the particular TB20 in this thread but clearly there are some difficulties in getting somebody to travel to it and spend time on it. You have to unscrew the belly panels (can be done by 1 person but a lot easier with 2) and then have a dig around and it’s going to be an all day job at least. It has to be somebody who can read wiring diagrams and follow the wires. And a lot of small aircraft operators in the UK simply do not have access to suitable or willing people. I too don’t (well not on a notice of less than about a week) which is why I maintain mine on a money-no-object basis. You can’t do this in most circumstances…

Administrator
Shoreham EGKA, United Kingdom

PA28 flaps do get stuck and lot of people heard the bang one day (probably, few know where it come from)

On prop vs power/break, I don’t worry too much about that: I just assume the aircraft does not have a front wheel (tricycle or tailwheel or tailskid) and I know exatcly where the stick should be and when the show must stop…

Paris/Essex, France/UK, United Kingdom

Pilot_DAR wrote:

That makes it sound as though one or both flaps could retract uncommanded. That would not be airworthy!

No, they’re locked upwards, but not downwards, so they can’t retract uncommanded. (Flaps move UP when retracted.) What could conceivably happen is that when you retract flaps, one side could get stuck while the other side retracts.

ESKC (Uppsala/Sundbro), Sweden

Peter is correct; the PA28 flaps are only “locked” in the true sense of the word when fully up, so they can be used as a step, other than that the lever mechanism holds it down against a spring force.

If the spring can’t do that, either is is knackered, or the hinges are too sticky. In most cases, the latter.

The only time I recall having the flap come up with a “bang” was in winter at cold temperatures, and the answer was to squawk it and, at the next opportunity, get the hinges cleaned and lubricated properly so the problem goes away (the hinges stick out below the wing and are exposed to muck, slush and water).

Last Edited by Cobalt at 17 Feb 18:51
Biggin Hill

Ibra wrote:

On prop vs power/break, I don’t worry too much about that

Unless the ground around the prop is perfectly free of debris, are you not worried about vacuuming up a whole lot of damaging material into the blades? The DA-42 I test flew had all six prop blades scrapped a few flights later (and before I got it back to continue) by the other pilot doing a full power ground run on pavement. I knew this, becasue after the weeklong delay in our test program, the plane returned with brand new prop$.

Airborne_Again wrote:

No, they’re locked upwards, but not downwards, so they can’t retract uncommanded.

Okay, I was thinking that flaps should be locked in the commanded position by a mechanism which prevents their uncommanded retraction, but I get what you’re saying now – I read the POH! I’m more used to Cessna, where the flaps will be where you select them, unless something is truly broken.

Home runway, in central Ontario, Canada, Canada
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