Since 2015, Alamo Liaison Squadron has been the owner of a beautiful 1944 Stinson L-5B warbird. While built for US Army Air Forces operations during WWII, in recent years this aircraft has flown in numerous events by the organization and has served to offer pilots flight experience in this unique aircraft type. The organization’s L-5, a.k.a. “Burma Babe,” was previously owned and operated by squadron member Fabian Fonseca. Following the airplane’s wartime service BuNo 17334 became civilian registered in 1956, and flew many years with the Civil Air Patrol, Nevada Wing. On Fonseca’s resignation from flying, the L-5 was offered to ALS, and for a short time the squadron owned two illustrious examples of the WWII workhorse, including another 1944 model, BuNo 17397, named “Delfina.”
Fabian Fonseca was a prominent member of ALS. He began flying with the squadron and kept his L-5 at Cannon Field as early as 2007. Fonseca “flew west” on October 26, 2024, and while his presence has been missed, like all former ALS members, he left a part of himself at Cannon Field. Born in January 1942, unbeknownst to family and the future pilot himself, this was a critical time in World War II, characterized by the formalization of the Allied coalition and the rapid expansion of Japanese territorial gains in the Pacific. Military campaigns in North Africa would be the precipice for the Allied march through Europe—the L-5 would play a huge role in both the European and the Pacific War Theaters. Fonseca served in the United States Air Force and served in the Vietnam War. He also flew the secretive Lockheed SR-71 Blackbird. This experience led to a continued love of flying in his retirement.
Experience Counts
According to the NTSB report, “the pilot reported that after touchdown, the airplane “lifted a little” and then exited the runway to the right.” In an attempt to correct, with left rudder and brake, “the airplane came to rest upright about 20 ft off the right side of the runway.” Certainly disconcerting for any pilot, passenger or observer, this type of incident, apart from the primary concerns over injuries to persons, raises the question, “What just happened?” Fortunately, both occupants of Burma Babe that day walked away shaken and stirred but not harmed.
The Stinson L-5 was designed and built in 1942, in response to a US Army request for a short-takeoff-and-landing light observation aircraft to support the war effort in Europe and the Pacific. However loosely one might define Observation as a role, the aircraft more specifically can be described by its Liaison function, even more plainly as a “Flying Jeep.” In its liaison function, or in general as an L-bird, the Stinson L-5 was an answer to two previous L-bird models subject to pre-war maneuvers, specifically the L-1 and L-4. The L-5 was a smaller and less complex, less costly construction to the very purposeful Stinson L-1. At the same time it was a heavier payload and slightly faster version of the Piper L-4. Regardless of the distinction, the L-birds, quite simply, performed any job that needed getting done.
One shortcoming of the L-5, one that was to be discovered only after its time in service, was its less-than-robust landing gear. As an aircraft particularly designed for rough-field, short runways, the L-5 was often found to buckle a knee, or two, when having to land, repeatedly, on less than ideal terrain. In the military this meant that spares were readily on hand and, most often, damaged aircraft were back in service in short time. The same fate of its main landing gear applied to its tailwheel.
A tailwheel aircraft landing gear configuration consists of two forward gear legs/wheels (under the weight of the engine) and a diminutive single wheel at the very aft of the aircraft, each supported by a shock or spring mechanism. On the L-5 this is exactly as described… the two forward gear legs are constructed of a large tapered tube that is supported on a pivoting cross tube with a shock absorber inside the aircraft’s belly. A smaller diameter, forward “strut” tube provides additional lateral support to the cross tube. The issue, however, is where the strut tube is welded onto the large tapered gear leg. In the welding process this area of the tube is “weakened” and, thus, small fractures can form in the tube. Over time the fractures can grow due to repeated stress on landing.
The above description is precisely what happened to the L-5 on that day, two years ago, in Pleasanton, Texas. The tapered tube supporting the left gear leg gave way effectively splitting the leg in half and embedding itself into the soft earth.
Normally such a single defect would immediately bring the aircraft to an abrupt stop and perhaps spin, or flip, the aircraft around that ground pivot. On this day, coincidentally, the tailwheel leg also gave way. The result was the fore and aft of the aircraft simultaneously becoming embedded in the ground.
The tailwheel design the the L-5 is such that two closely fitted tubes allow for a fuselage mounted cabane and a pivoting wheel on the other end to mate. One section slots into the other and is then secured by two bolts. The issue with this application is that the two mated tubes, over time, can retain moisture and this moisture promotes corrosion, or rust. In this incident the inner tube of the cabane failed due to unseen deterioration hidden inside the outer tube. Once the two gear legs, forward and aft, separated the aircraft effectively lost its ability to steer, much less roll freely once on the ground.
Progress
With most of the big questions answered, ALS proceeded with disassembly of the aircraft to assess and address damages. First, a set of newly restored landing gear was sourced and once reassembled the aircraft was back on its wheels. The second big step was the removal, delivery, repair and return of the aircraft’s left wing. As the aircraft came to rest following the incident on its right wing, the wingtip absorbed the weight. Constructed of wood and fabric, the fix was to rebuild a section of the wingtip by replacing damaged wood members. The expert assistance of an L-5 restorer (Sam Taber, Tab-Air) was enlisted and the repaired wing now sits ready to be final inspected and recovered. During the process, the crew at Alamo Liaison Squadron has been thoroughly inspecting and cleaning the aircraft. While this is done on at least an annual basis, it is now possible to access and see more. An eighty-two year old aircraft holds many mysteries!
Lessons Learned
While the NTSB report offers little detail on the cause of the incident, it does state, “the NTSB did not travel to the scene of this accident.” However, the team at ALS is well aware of the preventative steps now that could have been taken, and is focused on the restoration and on sharing its lessons learned in the maintenance and operation of the vintage L-5.
This same aircraft was down previously, for various periods of time, due to engine/oil/cylinder concerns, as well as a weakened condition of the horizontal stabilizer. The horizontal stabilizer was swapped out in 2024, while the original was rebuilt. It too is constructed of wood and fabric. The issue with this part of the L-5 is that moisture can enter the horizontal stabilizer and this can cause the wood at its aft edge to rot. The rotting is particularly evident in the area where it is hinged, and connected, to the elevator. The wood design is robust, however, the rot will gradually make the control of the elevator less effective. A technique for reducing internal moisture is the proper installation of drain holes and vent/vanes which was meticulously done on the ALS L-5.
Your Support Matters
Progress is slow and ALS is looking for volunteers to help with getting the aircraft back to flying condition. If you have experience with this type of work or wish to be involved in any way, including donations to facilitate the work, please contact us. We are grateful for any and all contributions.
Note: The L-5B was an Ambulance version of the type—as is the L-5 at Cannon Field—with a large door opening on the right side to permit the loading of a stretcher or cargo. It also had twin-float capability. In the RAF the L-5 was known as “Sentinel.” 729 of the L-5B were delivered to the US Army Air Forces. The L-5C model was the same as the L-5B but equipped with a vertical mount behind the rear seat for a K-20 aerial reconnaissance camera. 200 of the L-5C were delivered. Some 3,500 in total were built.