01W

U.S. Department Small Airplane Directorate

of Transportation Chicago Aircraft Certification Office

Federal Aviation 2300 East Devon Avenue

Administration Des Plaines, IL 60018

July 19, 2001

Mr. John DeJoris

President

Worldwide Aircraft Propeller Association (WAPA)

290 Larkin Dr.

Wheeling, IL 60090‑6456

Dear Mr. DeJoris:

This letter is in response to your letter dated July 17, 2001, concerning an alternate method of inspecting and qualifying blade shank and radius surface roughness of post cold compression rolled Hartzell single shoulder propeller blades. You provided a copy of the WAPA Inspection Procedure 001, dated July 17, 2001 for our review.

We have reviewed your procedure and met with you at your facility to witness the steps performed to inspect the surface finish of these fatigue sensitive areas. We found your procedure is acceptable to establish the cold compression rolling surface is uniform, free from defects, and has a final surface finish that meets or exceeds the minimum acceptable requirements to satisfy Airworthiness Directive (AD) 77‑12‑06 and/or Hartzell Propeller, Inc. continued airworthiness requirements.

Enclosed is a copy of WAPA Procedure 001, Hartzell Cold Compression Rolled Surface Roughness

Evaluation Process, stamped FAA Approved, dated July 19, 2001. Please be aware of your responsibilities in reporting any malfunction, defects, or failures associated with this procedure in accordance with 14 Code of Federal Regulations (CFR) part 21.3.

This approval is for the engineering technical aspects only. To incorporate this procedure into your WAPA Association's respective certificated propeller repair station's operational specifications, the document must be presented to your local Flight Standards District Office (FSDO) for review. The cognizant FSDO office will evaluate each respective certificated repair station for implementation.

If you have any questions, please contact Mr. Tim Smyth, of my Propulsion Branch at (847) 294‑7132.

Sincerely,

Thadeus D. Krolicki, Jr.

Manager, Propulsion Branch

Chicago Aircraft Certification Office

Enclosures