68-05-03: Reverse Mode

68-05-03 UNITED AIRCRAFT of CANADA, LIMITED: Amdt. 39-558. Applies to Models PT6A-6B and PT6A-20 Turboprop Engines. Compliance, unless already accomplished, with (a) required prior to further flight and with (b) or (c) and where applicable (d) within the next 25 hours' time in service after the effective date of this AD. To preclude either failure of the propeller to reverse or immediate reversing upon selection of reverse mode, the selection of propeller reversing is prohibited until the following inspections or replacements have been accomplished. (a) Install a placard in the cockpit in full view of the pilot that reads: "Do not Use Propeller Reverse". (b) X-ray teleflex reversing control cable terminals P/N's 3010175 and 30101495 to determine that a minimum of 0.08-inch wall thickness exists between cable counterbore and shoulder of threaded yoke arm spindle undercut. Reject terminals with thickness below 0.08 inch. (c) If X-ray is unavailable, disassemble the terminals and physically inspect in accordance with the instructions in United Aircraft of Canada, Ltd., Special Inspection No. 68-1 or an equivalent approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. (d) Replace terminals found below minimums with the same part number known to have sufficient wall thickness. (Spare terminals with walls verified to be in excess of 0.08-inch thick are identified with the letters DH within a circle marked on the hex of the coupling.) (The information in this AD is similar to that contained in Canadian Department of Transport AD No. DF-PT-68-2 issued telegraphically on February 6, 1968.) This amendment becomes effective February 28, 1968.