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Piper Control Wheel Lock

Hello,

As mentioned before, I recently took up flying the Piper Archer III (coming from the Cessna). All good.

One thing: The Cessnas come with a control wheel lock that is installed on the yoke after flight to prevent the control surfaces from moving around violently in gusts. The Piper has no such thing. There are after market solutions available, but the official POH recommendation is to use the seatbelts. Unfortunately, the POH does not actually specify the procedure how to correctly use the seatbelts for that. Further, the two PA28-181 I have flown now have different seat belt systems (the newer one has the car-like three-point system, the older one has the “regular” system with a seperate shoulder strap).

Does anyone have a detailed description or even a picture of how this is correctly done?

Thanks and cheers

Patrick

Hungriger Wolf (EDHF), Germany

With the separate lap strap/shoulder harness, forget the shoulder harness and feed the (extended) lap strap through the (P1) control wheel, connect it to the other part of the lap belt and tighten.

This keeps the horizontal stab trailing edge up and ailerons, hard over to the right. Don’t overtighten the belt and risk damaging anything. Using the P1 belt means you can at least get into the cockpit to sort things out without the harness being in the way.

Later 3 point belt should work similarly, with the shoulder harness extended.

It was said that using this method may promote corrosion in the stabilator, since water may become trapped inside. Don’t know if there really is any truth to it.

Mainz (EDFZ), Germany

Yes – a very bad procedure because it probably prevents the drain holes in the elevator from working.

There have been some severe corrosion cases in the TB series, clearly resulting from this practice, which have resulted in two SBs within the past year or two. The last one is very labour intensive because it requires de-skinning the elevator. Actually it is easy to inspect using a long endoscope but for some reason Socata didn’t go for that.

Before using any technique like this I would check where the drain holes are and make sure they are operative when the elevator is thus tied up.

Administrator
Shoreham EGKA, United Kingdom

Being a pedant, it’s a horizontal stabilator, not an elevator.

Also, the stabilator has an abundance of drain holes and furthermore, the method described is as instructed by the manufacturer and detailed in the Pilot’s Operating Handbook.

Being even more pedantic (;-)) in general the two concepts are called:
a) Horzontal Stabilizer + Elevator (Cessna)
b) Stabilator (Piper)

Last Edited by Flyer59 at 05 May 07:23

Locking the controls inside the cockpit by any means of poor form. I know that Cessnas provided control wheel locks, what a poor idea, I use them only if there is no other choice. Control system damage, which is usually serious, and nearly always hidden, can result from the air forces forcing the control against the control wheel lock, with all of the cables, bell cranks, pushrods and pulleys taking the abuse along the control circuit, and nearly none are pilot preflight inspectable. I have found (in flight) such damage, and can think of at least one accident (Twin Otter) whose cause was a damaged flight control cable from locking the flight controls at the cockpit. I prefer to use external control locks, and I make them for all of my aircraft. I do agree that external control locks on a stabilator are a challenge. Usually this flight control is less susceptible to gust damaged, if allowed to rest trailing edge down. Just make sure the drain holes are clear.

Both Pipers and Cessnas have horizontal stabilizer/elevator, or stabilator, depending upon the aircraft model. Each have their benefits and detriments. I do not prefer stabilator configurations for slow flight reasons.

Home runway, in central Ontario, Canada

What can not be liked about the slow flight characteristics of a (any except t-tail) PA-28?

On the TB, the control lock (in the LH yoke tube) locks the controls in the neutral position, which offers the least “catch” to any wind.

Where is the issue there?

There is no realistic possibility of modifying the locking options, short of a DER design package (DAR in Canada – I know ) or a massively expensive EASA 21 process.

Administrator
Shoreham EGKA, United Kingdom

Locking the flight controls at the cockpit assures that the controls in anything other than parked into a headwind, are “flying” all the time. In the case of a strong gust, there is potential for damage to the flight control system, which will likely be impossible for a pilot to detect during a preflight. You’d be horror struck to see a person handling an aircraft by the flight controls, how is it different when a strong wind is gusting from behind the parked plane, and forcing the flight control, through all the cables, pulleys, bellcranks and pushrods to the locked control wheel. Something has to give, and it will be something you cannot see. I’ve had such damage, which I found only in flight. A much more serious example here: http://en.wikipedia.org/wiki/Air_Moorea_Flight_1121

The PA-28 (and very earliest Cessna Cardinals) has a plain stabilator. These can be stalled (lifting down for nose up). My experience on several occasions on PA-28s from Cherokees to an Arrow, has been that a stalled stabilator will produce so much drag during a soft field takeoff, that the plane can be stuck in ground effect, unable to climb away for drag, with the only choice to land back. An elevator stabilizer combination can be higher drag in cruise flight, but at very slow speeds, with large pitch control inputs will increase the camber, so there is increased capacity to generate lift (down) before it stalls. The stabiliator generates lift only through AoA, so a stall is more possible.

What you gain one way, you loose the other. For low speed, high control deflections, I prefer elevator/stabilizer to stabiliator.

Home runway, in central Ontario, Canada
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