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-   -   PA28 stabilator control lock (https://www.pprune.org/private-flying/565688-pa28-stabilator-control-lock.html)

Hotel-Mama 4th Aug 2015 22:17

PA28 stabilator control lock
 
This post is prompted by a 05:30 visit this morning to the coastal strip where my PA28-180 is currently parked, to check that it was still the same way up as when I parked it...
The control locks I have inherited consist of a padded control surface lock for the ailerons (very simple, very effective), and a tube that fits over the yoke shaft holding the controls fully aft. Just thinking about that as the wind whistled about the chimney pots in the early hours, it occurred to me that yoke fully back is the worst possible position for it. In that position, the wind will acts to push the tail downwards, rotating the wings to take-off position. The tail tie down prevents the tail from lifting, but not moving downwards, and I suspect that wings that can produce a couple of tons of lift when demanded may prove too strong for spiral die downs in wet turf. I concluded that it was probably better to position the yoke neutral or forward, and hope that it stayed there... Obviously that is not very satisfactory, so I was just wondering whether any other PA28 drivers (particularly those who park in windy locations) have any suggestions for keeping the yoke in a forward position and for preventing the control banging in gusts? Given the swarms of PA28s around (to use a topical word) there must be some simple solutions out there.

27/09 5th Aug 2015 06:04

All I've ever used is the control column in the aft position and held in place with the lap with full left or right aileron applied. Worked every time.

tmmorris 5th Aug 2015 06:12

Hmm. The only PA28 elevator lock I've ever used has been the factory fit optional one using a pin through the yoke tube and it holds the controls basically neutral, certainly not nose-up. (It should come with a locking pin attached to a large red flag which blocks the mag switch so you can't forget to remove before start.) No idea if this can be retro-fitted.

mrmum 5th Aug 2015 07:29

I've got one that fits round the rudder pedals at one end and the bottom of the control column yoke at the other. This holds the c/c forward and the ailerons & rudder neutral.

Hotel-Mama 5th Aug 2015 10:41

Thanks mrmum; that sounds like just what I am after. I hadn't thought of using the rudder pedals as an anchor point. Is that custom made or just a simple locking strap?
I might just have a play with a roof rack strap to see what I can rig up (probably a tenth of the price of a specialist aviation one!). It is really only the stabilator that needs fixing. The ailerons are kept neutral by the external control surface lock, and the rudder is linked to the nosewheel. If the wind is strong enough on the rudder to move the nosewheel, the plane is likely to be upside down two fields away anyway!

Keef 5th Aug 2015 11:24

We had one like what mrmum describes. It wasn't that expensive, and I agree that tied down properly, nose-to-wind, yoke fully forward is the way to leave 'em.

9 lives 5th Aug 2015 12:15

PA-28's are a little more challenging to control cock than "stabilizer/elevator" configuration aircraft. I have been content to gently tie the control column fully forward, the plane will sit happily that way. It would be a very unusual wind which would force the stabiliator against that.

However, otherwise, I use the pin through the control wheel, or much worse seatbelt, only as a last resort. I know that manufacturers have provided that means, but I have repaired several Cessnas which have suffered internal aileron control system damage from the use of this type of lock. Such damage is easily cause, hard to detect, and expensive to repair. For ailerons I ALWAYS use the padded top and bottom locks between the flap and aileron trailing edges. To be sure, ti tie them forward, under the wing, to the tiedown ring, so they cannot slip off.

It is ideal to assure that you have parked your aircraft into the wind, and anticipated wind, whenever possible. Pilots forget this sometimes, and park neatly in a row with the other planes parked downwind, because the airport thought the tiedowns out poorly. I'd rather non conform, and prevent damage to my flight controls.

tmmorris 5th Aug 2015 16:16

Interesting, so does damage to the aileron controls happen as a result of the ailerons moving against free play in the system? Just wondering what caused the damage when using the pin lock.

Johnm 5th Aug 2015 17:15

I have one of the control locks that hooks round the rudder pedals and the yoke, it wasn't expensive and was bought mail order from the US as I recall

Chris Royle 5th Aug 2015 21:01

York Aircraft Gustlocks

Gustlock. Brilliant

Johnm 5th Aug 2015 21:18

239 USD they are having a laugh

mrmum 6th Aug 2015 05:58

Hotel-mama,
Mine was made locally, but looks like a copy of the York gust lock. If you want to look at getting one made somewhere near you I can send you pictures and dimensions if you want. I'd lend you it to copy if you were nearer, as the aircraft is normally hangared, so mine isn't used often.

Johnm 6th Aug 2015 06:22

Details of the one I got can be found at

http://www.finitesite.com/glarshild/windlock.htm

It's priced at $69 according to the site. That's roughly £50 and you can have mine for that as I don't have a PA28 anymore. I see you are in the next county so delivery or collection shouldn't be two much of a problem:)

Hotel-Mama 7th Aug 2015 09:06

Thanks mrmum / Chris Royle / Johnm. It looks like there are a few options. The York gustlock does look a little on the pricey side for what it is, particularly with the inevitable shipping / tax / customs, etc. The description on their website made me smile: "...the least expensive and most effective wind and theft deterrent insurance for your airplane you can buy"
Johnm - The Wind-Lock looks good, though I did have to find another website to see a picture (Aircraft Glare-Shields) I'll see what I can rig up myself for the time being, and when I have returned from my Scottish adventure (hence the breezy parking spots!), will PM you if a purpose-built solution like this looks like a worthwhile improvement.

9 lives 7th Aug 2015 11:23

A lock which restrains the control wheel is better than none at all, but to me, otherwise a last resort. Yes, it will lock the control wheel, but only locks the flight controls by requiring the internal flight control system to withstand the repeated pounding. I've known aircraft with bent aileron pushrods, cracked aileron internal structure, and bent and cracked pulley brackets from this. The Twin Otter crash in Moorea years back was attributed to gust locks being applied in the cockpit, and the control cables taking the ground gust loads.

The ailerons and rudder seem to generally be more vulnerable to gusts than a "down" elevator or stabilator.

I agree that on a PA-28, the stabilator is very hard to lock externally, so control wheel restrained full nose down may be the best you can do, but ailerons should have external locks on them - my planes ALWAYS do when they are outside.

topoverhaul 9th Aug 2015 16:54

When I had an Arrow, I used to just fold the seat back forward to 45 degrees and then slide the seat forward until it held the column in the fully forward position.
Zero cost and very effective.

Hotel-Mama 15th Aug 2015 15:08

topoverhaul - You are a genius! I just had a chance to try your method, and it works really well. I have to admit I was a little surprised at how securely the seat holds the controls wedged in a downwards position. I wonder why this is not more widely known compared to the widely used but deeply flawed method of tying the controls back with the seatbelt.

Beenaroundabit 15th Aug 2015 16:00

We use a common bungee chord with a hook either end. We push the yoke fully forward and stretch it through both yokes tying them together. That way it stays forward and hold the ailerons level too. Very effective and costs a quid. Never failed and the plane has been tied down outside for years.
https://dl.dropboxusercontent.com/u/42644035/Bungee.jpg


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