Trim inspection plate

[Laz]

I feel like I have never ending need for obscure information. I sure which a set of drawings for the BC12D were available. Absent that here is my latest question.

What kind of inspection plates , if any were originally installed on the elevator bottom side for trim inspection mant. ?

Also there is a small 45 degree angle cross base on the rudder. I do not think that it was originally rib stitched that brase lower than the other rudder ribs. I did see at least one Tcraft with stitches on that brace as I searched the treads to find the answer to my trim inspection cover question. I did see that Bob Lees used two inspection rings on his trim tab area. My only problem is I’m not convinced that the covers would stay if they were actually cut out.

One last thing . What ate the best inspection plates to use on a T-craft.

Tanks

[Pearson]

Re: Trim inspection plate

Laz,

I share your concerns for providing an inspection area on the bottom of the tail. I am not sure if a regular round type inspection cover would stay on there. I would be curious to hear from someone who has covers there.

There are inspection plate covers that have two small round projections welded onto the spring tab that holds the cover in place. These two projections are the same distance apart as the ID of the inspection hole. They keep the cover from sliding to far in either direction once it is in place. If anything would stay in place, that should do it. They can be a bit of a bear to remove. The only other thing I can think of would be to install a piece of aluminum sheet held in place with small screws, just like the inspection hole on each side of the vertical stab.

[Hank Jarrett]

Re: Trim inspection plate

I have covers on the top and bottom of the trim jack screw area as well as for access to the elevator horn area. According to what the FAA types have told me the circular snap rings are supposed to only be used on lower surfaces. Upper surfaces are supposed to have panels held on with PK screws into a fabric reinforcement under the hole. When I asked about the horizontal tail I was told the rule was the same.
Ready for it? I asked WHY the round ones were only on the bottom and the screwed ones were on top and was told the low pressure surfaces had to have screws, but the high pressure surfaces could use the snap in round ones. Think about that for a minute. On the elevator the LOWER surface is low pressure and the TOP is high in cruise! When you deflect the elevator EITHER surface could be low or high. I got looked at like a deer in a spot light and never got an answer.
As to what's on my plane, the attached picture shows the fuselage with the elevator horn side covers off. They are held on with screws. If you look close you can see the screwed on cover hole on TOP of the elevator. There is a snap on round cover on the bottom just below it and there are snap on covers under the stab for access to the tail.
I have never lost a snap on cover.
Hank

I can't believe with as many pictures I have taken of tail springs I never got one that shows the access holes just above them!

[Howard Wilson]

Re: Trim inspection plate

Another trick I've seen is to run screws thru a regular round inspection plate thru the fabric and into the tension strap on the inside...... just sayin' h

[cvavon]

Re: Trim inspection plate

Jest a note on rudder side plate covers the top center screw has to be shorter or will hit elevator horn and cause problem Chuck

[Hank Jarrett]

Re: Trim inspection plate

Also good to think ahead and DON'T put a screw right behind the stab root rib. You can't put the tail on with the covers on and you can't put the covers on with the tail on.
Don't ask.
Hank