Maintenance Matters

Massive TCM crankshaft fiasco puts many owners on the beach.

At least they can heave a sigh of relief in Williamsport.

Just as Lycoming was digging out from a widespread problem with piston pin plugs, Teledyne Continental got its night in the barrel with a massive crankshaft AD affecting 3200 engines with cranks made in 1998. As we go to press, TCM was fanning inspectors into the field as shops were popping jugs to open up each engine for ultrasonic inspection, a process that takes less than an hour. Following that, the engine is buttoned up and returned to service, with costs covered by TCM, to include the cylinder R&R and crankshaft replacement, irrespective of warranty state.

Seven Failures
TCMs John Barton told us the problem first came to light last December following the failure of a crankshaft in an IO-520. Two other crankshaft failures were reported last year and four this year for a total of seven. All but one aircraft made safe landings on runways; one was damaged in an off-airport landing.

Barton said TCMs internal investigation revealed that an unknown number of crankshafts were damaged during manufacturing by a hydraulic ram used to press in bushings for counterweights. One of the rams guide rails was broken which evidently allowed the tool to cant slightly, causing a dime-sized nick which penetrated the cranks nitrided surface.

Barton said TCM believes the earliest damaged crank was manufactured in March of 1998, but to be conservative, the company is applying the service bulletin/AD to all cranks made in 1998, for remans and replacement parts. The AD applies to 470, 520 and 550 series engines.

Yank the Jugs
TCM immediately notified all known owners by letter in late April, the FAA issued AD 99-09-17 describing the fix. It involves removing two cylinders, pistons and rods to expose the potentially damaged area of crank cheeks number 2 and 5 for ultrasonic inspection, which is being done by a team of TCM inspectors.

If the crank passes inspection, the engine can be reassembled and returned to service. If a damaged crank or a crack is detected, the engine is to be removed and returned to TCM for overhaul, at the companys expense.

TCM has allotted $700 for cylinder R&R for normally aspirated engines, $900 for turbocharged engines. Its also providing the parts and pieces necessary to return the engine to service. Rather than have any and all shops perform the work, TCM is asking owners to call its hotline (888-200-7565) to schedule the work so that inspectors can coordinate traveling from airport to airport. For engines with fewer than 300 hours, the inspection must be done within the next 10 flight hours. For those with more than 300 hours, the inspection period is 50 flight hours.

Howre They Doing?
With so many engines to open up, we expected to see massive shop bottlenecks in some areas but as of early May, the inspections seem to be progressing apace, with spotty complaints here and there. In Alaska, one inspector reportedly shuffled off to his next appointment before completing some engines awaiting inspection. Another shop complained that inspectors were supposed to show up with gaskets and other reassembly parts but didnt. One owner told us that a TCM inspector was encountering a 20 percent failure rate which, if true, will require overhauls on 600 engines.

We checked with three shops and were told that although the $700 allowance for cylinder R&R may be too little, TCMs inspectors are generally showing up as promised. (In early May, the company added 30 inspectors, for a total of 40.)

Only one shop-Arapahoe Aero in Denver-reported that a crank had failed inspection. But another, Banyan Air Service in Fort Lauderdale, Florida, reported finding damaged babbitt on rod bearings in two engines, a problem the shop said it was addressing with TCM.