I just got this email from my friend (A&P IA) in Texas who was finishing up the engine re-install on 96V. Getting ready to test fly the plane, he noticed a problem with the flaps and upon closer examination sent me this:
We looked at the flaps yesterday…. they have slings inside the wings that provide the up-tension, each flap has a separate cable that goes to a turnbuckle just above the rear passengers heads, these turnbuckles join to one cable that is routed through pulley's back under the floor to the Johnson bar flap actuator. It appears to me that there should be a spring somewhere from the Johnson bar to the single pulley to add tension to the system counterbalancing the spring in the flap itself. What is happening is that the actuator arm at the flap is way to loose in one direction and is scraping on the aileron cable… this is happening on both sides, but the left is a problem and the cause of the noise, rumbling feel when you put the flaps down (the left is worse than the right and the reason the wind blew them independently). I've included pictures for you of the left… you can see that the ball end of the cable is loose allowing the bracket to drag on the aileron cable.
Airplane is in Texas and I'm home in Virginia. Has anyone seen problems like he is descrbing before in '48s? Any ideas how to make it right? I am not sure I totally understand the issue he is describing.
Photos attached.
C170- left flap actuator-1.jpg
C170- left flap actuator-2.jpg
C170- left flap actuator-3.jpg
C170- left flap actuator-4.jpg
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According to the IPC there is no other spring, just that is suppose to hold the flap up. On the A model which has essentially the same system there is a lock that is suppose to hold the flap locked up until the flap handle is pulled but they seldom work and when they do can easily be over come by wind.
I believe what he is showing you is the end of the cable with the flap held down. In this state the cable is slack and has no where to go and in your case the clasp is sliding up and down the cable. Tell the mechanic not to hold the flap down and everything should be OK and also tell the mechanic to insure the flap is secured with a lock device between the flap and the fuselage fearing when outside. Of course if the cable or clasp is worn because of the flap being blown willy nilly over the years, it might be time to replace them.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Assuming you have the proper length cables installed, they should be adjusted to be snug when the flaps are up and the lever is down. as soon as you move the lever up, the flaps should start to move.
I agree with Bruce, tell your mechanic to let go of the flap, and operate the flaps with the handle as they should be.
It is a 1 cable system. there is only a down cable, no up cable. just a spring to return the flap to the up position.
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