Thorp Air Command - T18.net

I have a few maintenance questions that I've been harboring for some time. This thread is in "Miscellaneous" because of the variety of content.

Here goes!

1 - Flap Deflection Limit: The Thorp I bought does not have a mechanical or electrical limit at 30 degrees flaps. It has a simple momentary rocker switch and some visual indicators on the flaps. Given the consequence of higher flap deflections, I would like to find a method that prevents the flaps from excessive deflection in case I hold down the switch too long or if there's an electrical failure.

What methods have you used to prevent electrically- or manually-driven flaps from exceeding 30 degrees?

2 - Jacking Method: I had a flat tire recently and we resorted to agricultural methods to jack up one side of the aircraft. What methods/devices do you use to jack up the aircraft? Do you put a modified jack under the wheel hub or clamp somehow to the round gear?

3 - Squeaky / Creaky Tail Gear: My tailgear has recently exhibited a squeak or creak when the airplane settles a bit in yaw (on the ground). Have you heard this before, and what did it end up being?

4 - Control Lock: Do you use a control lock when parking the aircraft outside? What's a good method to prevent the control surfaces from banging around from the wind? Did you make something custom, use the seatbelt, or buy an existing product?

5 - Instrument Panel Hole: I'd like to add a G-meter to my panel and I'm looking for clean ways of making a new hole / cut-out in the panel. There are a few options on Aircraft Spruce from cheap to pricey. What's a good choice for something reasonably-priced to cut one or two holes in an existing (and somewhat busy) panel?

6 - External Camera Mount: Where and how do you mount GoPro (or similar) cameras on the outside of the aircraft? I have been using the under-wing tie-down loops, although I'd like to explore new mounting locations. Also, when I mount a camera under the wing, I can't access the remote control feature (RF blockage), so I have to set record before the flight and it continues recording until I land or it runs out of battery/memory. Mounting it on top of the wing or on the tail would give me line-of-sight and let me control it in flight.

1. Move the limit switch.
2. I’ve had success placing a scissor jack under the nut on an axle bolt.
3. Inspect to see what’s moving.

D

1. I would look into installing a down limit switch or, depending on how the flaps are operated, adjusting the mechanism so it cannot travel farther than desired.

2. I use my floor jack under the landing gear strut to lift one side to remove/install wheels. I have also used the tie down rings as jacking points to lift both sides at the same time to put it on the scales.

3. See what came loose or wore out.

4. Seat belts for the stick. The builder used a u-shaped piece of sheetmetal to hold the rudder peddals together.

5. There are several ways to cut holes. The correct hole punch is best. A hole saw is probably the worst.

6. I don’t trust plastic camera mounts at Thorp speeds. I have heard too many tales of broken mounts and lost cameras. I mount mine centered between the seats so it shoots over my right shoulder.


I hope some of that helps.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

someone on here once posted a small jack that was home made. He had welded a "V" angle on top of the threaded rod. The rod was raised using a union (and rotating that union). Cant recall many more details than that. I thought it was a great travel jack to use in an emergency. I use a common floor jack if one is available. I think I recall seeing a way to clamp a jack to the round gear legs in the newsletter.

I had a creaky tail area one time! Its been a while since it happened, but it seems like I raised the tail just enough to get a block under the tail spring and then it seems like I re-snugged a bolt or two, but I cant recall if is was on the bolster or the tailwheel assembly. Anyway, whatever was creaking went away after I snugged up a bolt or two back there.

For the tire I will get a picture of Ron's custom jack. It worked really well and made short work of the jacking up part of the tire change (cowling was a different story).

Given the less than ideal conditions in an agricultural environment and the tendancy of most people to go overboard to safely keep $200k+ equipment from falling to the ground during jacking operations, I would think it would have been a pretty good solution on level concrete. Although, loaders and forklifts aren’t very portable if you chose to hoist the aircraft with one.

_________________
Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Control /gust lock . Can't take credit for this our good buddy John Evens came up with the design . Nothing more that some spare 3/4" tube , angle and tubing cut to make circles to fit over the rudder pedal legs . The top portion has a small section of nylon cut to fit around the control stick and tighten down with a threaded rod . If you have dual brakes this set up probably won't work .

RB

For jacking I drilled a hole in the bottom main spar just inboard of the wing joint (each wing). It has a 5/16 NC PEM Nut inside. To lift, I simply bolt a large block of wood there underneath with a bottle jack. Some have made special attachments for the jack, like ball and socket to prevent slipping. The main idea is to have uninhibited access around what you're working on, such as wheel pants, wheels, and brakes, without worrying about bumping or knocking the work off of the jack. In my case, I also find it a safe thing to tie down the tail end depending on CG.

Les

For jacking I tapped the inboard side of the gear leg with a 5/16 - 18NC thread. I install a short 5/16 cap screw and washer. This lets me use a small hydraulic jack to lift the wheel up. The washer keeps it from slipping off of the cup on the jack.

Jim

A guy here made this tribal jack a couple of years ago. No one ever gave it a try until today when I used it to do the wheel bearings on an AgTruck (the engine hoist is buried and will be brutal to dig out). This jack is too light for serious use on these airplanes. To much side load is causing the jack to bind while extended. I had to use a mallet to coax the jack to collapse but it may be a good solution for a Thorp since they weight less than half as much and wouldn’t need to lift as high. It’s just a cheap bottle jack with some scraps welded to it to catch the bottom of the strut. The AgTruck was very stable on it.

_________________
Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

1. no good info from me

2.Changing tires on mine I took the top cowl off and lifted by the engine with an engine hoist to get at my tires. Was easier than fabricating something at the time. If you have time to fabricate I would say the above mentioned methods look good.

3. since the tail wheel swivels to be inline with the direction of travel I would say it might be in the wheel bearings on the tail wheel. I'd lift it up and start moving parts to see or have someone move it while you are down by the wheel.

4. Many take some small thin blocks of wood, 2 pieces, drill a hole in the middle and use a long bolt with a wing nut to place between the ailerons and flaps to hold them. Put felt on the wood pieces to keep from scratching. I personally just use a bungee cord from my stick to the rear bulkhead. Holds tail back and keeps the stick somewhat centered. I wouldn't trust it in heavy wind.

5. Nothing but a hole cutter/punch. You can get them for around $50 on aircraft spruce. Drill small hole, put them on the panel and screw down. Makes perfect holes. Any type of drill hole cutting device never works as well and can get scary cutting through a panel with wires behind it. Most shops carry the instrument hole cutters so you might be able to borrow/rent one for cheap. I just bought the A&P a 6 pack of his favorite brew and was able to use it for the day when making my panel.

6. I use gopro sticky mounts. I have one mounted on the wing tip towards the fuse and one mounted a few inches behind leading edge on top of the inner wing facing forward. You will need the slightly curved ones. If you clean the surface with alcohol then make sure the surface is warmer than 70* it will stay. It needs 24 hours to fully cure. Gopro also has secondary smaller stick ons with a high tensile wire attached that you secure to the camera. It's basically a back up if the original mount gives way the camera doesn't go anywhere. I also have one mounted on the turtle deck between the seats. So far even up to 205mph my wing mounts have held strong. The key is surface prep and the quality stick ons with the 3m adhesive.

My hangar mate and RV driver lets me use this lifter. It works great. He doesn;t recall where he got it.

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Base: KALX
N8786
SN 929

Does he know where his RV is ?

RB

Just saw this on the Fly Boy's web site, might work for a Thorp
https://www.flyboyaccessories.com/product-p/7211.htm

_________________
Bruce Finney
N18JF T-18C #262
Yelm, WA USA

A floor or scissor jack under the axel bolts works fine .. no need for special gadgets.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD