Matt Dralle - Experimental Aircraft Builder's Log

Matt Dralle's RV-8 Project

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Date: 2-28-2010
Number of Hours: 1.50
Manual Reference:
Brief Description: Hartzell Prop Bolt Torque & Safety Wiring - Part 1

It was time to torque those Hartzell Prop bolts. I bought a special little wrench extension Avery that is designed to specifically allow you to tighten the Hartzell bolts using a standard 1/2" torque wrench. Normally, if you added an extension to the end of a torque wrench, you'd have to recalculate the torque read out because of the added mechanical advantage afforded by the extra length of the extension. However, if you keep the extension at a 90 degree angle to the torque wrench as shown in the picture, you don't get any added mechanical advantage and don't have to recalculate the torque values! Sweet. My Hartzell CS prop, C2YK-1BF has a "K" flage and according to the manual requires 60-70 foot/lbs of torque. I set the wrench to "65 ft/lbs" for good measure and tightened each bolt alternating in a cross pattern. Once the bolts were tight, it was time to safety wire them. There is a little roll-pin in the head of each bolt that you're suppose to thread a safety wire though and safety the bolts in pairs. Since you have little-to-no control of the ending position of these roll-pins, getting the safety wire though them such that they will hold the bolts tightly can be quite a challenge. But, once I did the first one, the second two pairs went pretty smoothly.

Avery Prop Bolt Extension

Wrench At 90 Degrees

Torque Set To "65 Foot-Lbs"

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