53-04-01 PIPER: Applies to All Model PA-18 Aircraft Which Have Not Had the Control Stick Retention Device Modified to Incorporate a Through Bolt.
Compliance required by April 1, 1953.
In order to prevent the control stick inadvertently pulling out of the socket, continue the existing hole for the retention pin on the quick detachable control stick spring device through the control stick and socket and install an AN 3-14 or AN 3-14A through bolt.
(Piper Service Letter No. 162 dated March 6, 1951, covers this same subject.)