Pa-31-350 Cracked Forward Wing Spar Bulkhead
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Cracked Forward Wing Spar Bulkhead
Right Rear Bulkhead Reinforcement installed.
Left Rear Bulkhead Reinforcement installed
Left Front Bulkhead Reinforcement installed.
Right Front Bulkhead Reinforcement installed.
Forward Wing Spar Bulkhead Reinforcement
Discovered during the teardown inspection performed by the National Institute for Aviation Research, Wichita State University. Page 284 of Teardown Evaluation of a 1975 Piper Navajo Chieftain Model ... - FAA
Believing in proactive maintenance practices, 6 additional aircraft with total times ranging from approximately 7,000 – 16,000 hours were inspected. All four forward wing spar attach bulkheads on all Chieftains inspected exhibited similar cracks to those found in the tear down report.
At the time we had more than 20+ years maintaining Navajo’s and were familiar with Piper Service Bulletin 1045 from September of 2000 addressing this issue on the PA-31 and PA-31-300 aircraft. SB 1045 used a sound and logical approach to repairing the damage,requiring you to replace the forward wing spar attach bulkheads with thicker stronger parts. The time required to do so was extreme. It involved disconnecting the fuselage from the wing at the forward wing spar attach bulkheads. Not unlike knee surgery it left the body or fuselage of the aircraft without a sound leg to stand on. Additionally it also required cutting a large wire bundle running down the right side of the aircraft through the parts being replaced. This large wire bundle carries the wiring that goes to the pneumatic and auto-flight systems along with several other systems. Cutting and installing a large connector in this wire bundle can be intimidating to say the least.
As a solution we developed a kit, in conjunction with Piper Engineering, that nests inside the Forward Wing Spar attach bulkhead. As the original bulkhead bend radiuses are too tight to use 2024T-3 the kit uses 2024T-0 pressed in dies and heat treated to match the bulkhead it is reinforcing. It comprises a compound bend, to follow the exterior curvature of the airframe, and is joggled to accommodate over lapping joints so that it matches the material originally used during manufacture. It was more than two years in the making and is a Piper Approved one time, reinforcement or repair.
To date we are aware of more than 24 Chieftains across America from Florida to Alaska that have been inspected with total times ranging from approximately 2,000- 36,000 hours. 100% of the aircraft inspected have had cracked Forward wing spar attach bulkheads.
Our kit is a one-time reinforcement / repair that solves this problem simply and quickly. Total average installation time is approximately 16 hours, or 8 hours per side to completely install the kits we provide.
In working with Piper on this repair, discussions of Service bulletin and Maintenance Manual revisions have come up. Please take advantage of this proactive maintenance approach and consider your purchase before a Service Bulletin or Maintenance Manual Revisions is issued.