PIPER AIRCRAFT, INC.
PA-28-161, WARRIOR III
MAINTENANCE MANUAL
PAGE 1
Nov 30/064G21
57-10-00
MAIN FRAME
1. Wing Spar Inspection
WARNING: FAILURE TO FULLY COMPLY WITH THIS INSPECTION COULD SERIOUSLY AFFECT
THE STRUCTURAL INTEGRITY; SAFETY AND AIRWORTHINESS OF THE AIRCRAFT.
A. Background
On March 30, 1987, a PA-28 engaged in pipeline patrol operations suffered an inflight wing
separation resulting in a fatal accident. Investigation revealed the wing failure was due to
propagation of a fatigue crack, which originated in the wing lower main spar cap.
Based on more than five hundred (500) inspections of PA-28 and PA-32 airplanes with more than
5000 hours total time-in-service, and extensive wing fatigue and fracture analysis by Piper, the
following inspection requirements have been developed.
NOTE: In the course of the inspections cited above, only two (2) negative findings were reported
on a pair of PA-32’s operating in a severe environment and with considerable damage
histories. Piper understands that the majority of aircraft are, have been, and will continue to
be operated well within the aircraft’s design parameters during all of their operational life.
HOWEVER, Piper also realizes that some small number of aircraft engage in operations
which are defined herein as “severe” or “extreme” and those airplanes will require more
frequent wing removal and inspection.
B. Procedure
First, determine the airplane’s “usage class”; second, determine the recurring inspection intervals;
and, third, when required, accomplish the wing spar inspection.
(1) Determining Usage Class
NO
TE: Airplane operating history and usage class are established during initial compliance
with Piper Service Bulletin No. 978A, check the logbook entry.
Complete documentation and/or knowledge of the airplane’s entire operating history is
required in order to make a valid determination of “Usage Class” and inspection intervals.
(a) Usage Class “A” - NORMAL
All aircraft which do not and have nor engaged in operations considered as “Severe”,
“Extreme”, or “Unknown” in the Usage Classes described below. Most aircraft will fall into
this “Usage Class”. Normal flight training operations fall into this class as well.
NO
TE: If there is any doubt as to the airplane’s operating history, it is recommended that
the initial inspection be conducted in accordance with the “Next 50 Hours”
inspection requirement, below.
(b) Usage Class “B” - SEVERE
Aircraft which have engaged in severe usage, involving contour or terrain following
operations, (such as power/pipeline patrol, fish/game spotting, aerial application, aerial-
advertising, police patrol, livestock management or other activities) where a significant
part of the total flight time has been spent below one-thousand (1000) feet AGL altitude.
NO
TE: Aircraft with part of total time-in-service in Usage Class “B” operations and part in
Usage Class “A”, may adjust inspection intervals by a “Factored Service Hours”
calculation. See “Factored Service Hours,” below.
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