53-24-04 PIPER: Applies to PA-18, Serial Numbers 18-1 to 18-3000 Inclusive; PA-20, Serial Numbers 20-1 to 20-928 Inclusive; and PA-22, Serial Numbers 22-1 to 22-1689 Inclusive.
Compliance required not later than February 1, 1954.
In order to preclude the possibility of loss of fuel and hydraulic oil and fire in flight caused by chafing of these lines between the firewall and muffler, the following should be accomplished:
(a) To prevent contact with the muffler, reroute the fuel primer line, and wheel brake hydraulic line if necessary, so that they do not pass behind the muffler.
(b) Use clamps to fasten the lines to the firewall to prevent movement and vibration of these lines.
(Piper Aircraft Corp. Service Letter No. 213 covers this alteration.)