This section A-A above is typical from Piper’s assembly drawings. Check the torque on the hardware where the long bolt attaches the rod end bearing to the strut. If that bolt, either AN8 or AN9, is allowed to rotate from inadequate torque, then the gear door retraction bracket likewise can move during the retraction operation, thereby disallowing proper gear door adjustment. Also look for a bent bracket (see image above) which is quite common after 45 year’s service. Here are the torque values for the long bolts: AN8 = 480 – 690 in-lbs dry; AN9 = 800 – 1000 in-lbs dry.
Note concerning 6-39, C on page 1. The 0.125” deflection means exactly that; you must have some deflection or the closure load on the door is excessive. Excessive and you may have a bent bracket, and stress the gear door near the hinge causing a crack, which is why you typically see that ugly patch repair at that location – again see the photo of the poor fit job after a repair above.
If you plan on doing a bunch of these gear door adjustments, here is a tool suggestion. Purchase an Easy-Adjust Threaded Connecting Rod, 4″ Overall Length, with 1/4″-28 Threaded Female Ends. This rod is aluminum, hex shaped, and has a left hand and a right hand threaded end. Also purchase male threaded rod end bearings and the jamb nuts, one each LH and RH. Use this tool in place of the retraction rod for the adjustment mentioned in 6-39, C. Mimic the length for each retraction rod and install the retraction rod with the correct length preset. You’ll spend about $60 for materials on this tool. See the tool photo below.
Another problem seen in this main gear door area is a damaged, broken, or missing door stop bracket; see the photos and the discussion below.
The main landing gear door stop is a small plate which I have named the “main gear door stop plate”; it is riveted to the wing at the rear of the gear door opening. The purpose is to help align the retracted gear door flush with the lower wing skin. The thin gear door stem bumper P/N 453-887 [in the twins it’s P/N 453-641] is also located here; without that bumper you will chafe the aluminum. And please don’t drill a larger hole to accommodate whatever bumper you can find at the hardware store. Let me know if you need the bumpers; I have both the thick and thin styles. These bumpers are included in my landing gear wiring replacement kits, and the landing gear push/pull cables [conduits] installation kits.
The most common cause of damage to this plate is from improper routing of the brake hose. Possibly when the brake hose is removed and not properly routed and secured when reinstalled, it can foul that plate upon gear retraction. See the damaged plate in the photo below and the drawing insets on pages 6 and 7 which show brake hose routing.
Another less common condition is improper orientation of the AN4 bolt at the gear fork where the strut oleo tube fits. If that bolt head is not aft, the lower torque link will touch the bolt. Then the oleo will not fully extend and the pivot between the torque links will be too far aft and consequently contact the plate and bend it upon retraction. This can be assembled incorrectly after tube replacement or other service/repair.
And yet another cause; retracting the gear with a deflated/compressed oleo.
This plate is not to be found by me in the parts catalogs [I have wasted way too much time looking, but it has to be there!], and one would assume it would be like so many other Comanche parts, NLA. So I had a fabricating shop make a set of forming dies to duplicate the plate including the joggle. I felt a doubler was a good addition; they’re $30 each which I know is too much. Remember I had to pay for the forming dies and forming the parts. Since this is an un-approved part from me, it might be a good idea if you did the “ownerproduced” route; or just fabricate your own – that’s called a disclaimer in legal parlance.