Why does nobody talk about how much torque a simple flap linkage uses

Was re-rigging a Cessna 172 flap circuit last week and grabbed my 1/4 inch drive torque wrench out of habit. Checked the manual and it said 35 inch-pounds on the pushrod bolts. That's barely more than a firm handshake yet I see guys cranking them down with a full ratchet all the time. Anyone else notice how often we overtorque small hardware on GA birds?

3 comments

3 Comments

hannahcraig14d ago

35 inch-pounds feels like nothing but I stripped a Cessna 150 flap bracket bolt last month thinking I knew better.

david_reed2214d ago

I heard a mechanic say 40 inch-pounds is where most people strip those tiny bracket bolts.

josephbailey14d ago

Did you catch that old EAA safety article about torque wrenches and small hardware? I read it a few years back, and it stuck with me. They tested flap bolts on a bunch of Cessnas and found that over half of them were overtorqued, some by almost double. The problem is folks think they need to feel a good snug, but 35 inch-pounds doesn't feel like much with a regular ratchet. That article said a lot of those bracket strips happen because the aluminum just gives out before you even realize you've gone too far. It's a good reminder to trust the manual and not your arm.