Wing Spar AD’s
AD 2001-13-18 calls out the continuous eddy current inspection of all T-34 aircraft wing spars at 80 hour intervals with additional flight restrictions. This is a very invasive inspection each time and can eventually destroy the spars. We are installing two Alternative Methods of Compliance (AMOC) to this wing spar AD on both the T-34A and T-34B model aircraft. These AMOC’s eliminate the continued eddy current inspections and will return the T-34 to its original unrestricted flight envelope. The two options include the installation of new Beechcraft common spars in your T-34 Mentor, or installation of the reinforcement “Doubler” plate on your existing spars. Both of these AMOC’s are STC’d FAA approved procedures.
STC SA5529NM (Common Spar)
The installation of new spars in the wings of the T-34 will provide an additional 25,000 hours life to the wings as well as a substantial increase in strength to the aircraft. As can be seen, the new spar is a solid web out to the wing tip and the wing attach fittings are much larger. This is the same style spar installed in new Bonanza and Baron aircraft. This installation also provides the ability to inspect areas inside the wing structure and repair any corrosion or hidden damage. It also is a convenient time to install new wiring, fuel cells, and paint wheel wells. Beechcraft is currently manufacturing spars for new production piston powered aircraft and in support of the T-34 AMOC.
T-34 Spar Corp. AMOC-1 Doubler Plates
We are also performing the installation of the spar reinforcement plate or “Doubler Plate” as it is commonly referred to. This AMOC involves the eddy current inspection of the spar followed by the installation of a high strength machined aluminum plate onto the spar web in the inner wheel well area. The plate can be seen installed on the spar in the photo. This area has been identified as requiring additional strengthening for continued safe operation of the aircraft. Installation of the doubler plate will provide an additional 7,500 hours of service for the original spars.
STC SA10835SC T-34 Spar Corp. WS66 Doubler Plates
These doubler plates are installed on the lower cap of the rear spar spanning the main landing gear attachment trunion. Once installed, the 80 hour rear spar inspection intervals are raised to 3,000 hours, and can be used in conjunction with either the Common Spar or AMOC-1 doubler plate forward spar modifications.
