Lycoming is recalling 391 crankshafts which, it suspects, may suffer from the same metallurgical problem that affected hundreds of others the company has already replaced.
“It’s not a new problem,” said Ian Walsh, Lycoming’s general manager. “It’s the same type of problem – subsurface defects – that we had before.”
All of the suspect shafts were forged by Interstate Southwest Ltd., he said. “They’re non-conforming. They were overheated in the forging process,” he stated. Walsh pointed out that Lycoming monitors the performance of all crankshafts forged by Interstate, looking for changes in performance. The current recall is the result of a single engine failure on a light twin, in which no accident was involved, he said.
Of the crankshafts being recalled, 308 went into new engines built by Lycoming, Walsh said. Some of the others may have been used in overhauls, some may still be in stockrooms. He said that 80% of the affected shafts have been identified and about 80% of those have been replaced or are scheduled for replacement. “They’ll probably all be done by late summer,” he said. “We’re applying lessons learned from the earlier recall and it’s going well.”
All of the shafts being recalled were made for 360-series engines. These include (L)O-360, (L)IO-360 and AEIO-360 models. Most are mounted on a variety of Cessna, Beechcraft and Piper airplanes, although a few were employed in foreign aircraft and a couple of blimps, according to the Lycoming website, where a list of affected serial numbers is available.
Lycoming’s legal wrangling with Texas-based Interstate continues, Walsh confirmed. Last February, an East Texas jury concluded that structural deficiencies in crankshaft billets supplied by Lycoming were at fault, and not overheating during Interstate’s forging process, as Lycoming claimed. The jury awarded Interstate $96.1 million.
Not surprisingly, Lycoming is “vigorously” challenging that verdict. The company’s own technical analysis disagrees with that of Interstate, Walsh said.
While Walsh said that there are “a lot of reasons” for Lycoming to be confident that it will prevail, he could not go into the technical details at this point, in part because he has not been involved directly. His advice to anyone curious about those details: “Look back at the older information. It’s the same type of problem now. While the circumstances are different with these crankshafts, we’ve confirmed that the problem is the same – subsurface defects caused by overheating.”