TCM Crankshaft Situation
(as Reported in AVweb NewsWire)

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Supplement to Mike Busch's article "Firsthand Look: TCM Crankshaft Inspections."

ATISApril 12 | April 19 | April 26 | May 3 | May 10 | May 17

Monday, April 12, 1999

Crankshaft Problems Plague Teledyne Continental Motors

New TCM Crankshafts Breaking In 520/550 Engines...

At least six new and factory-rebuilt Teledyne Continental Motors (TCM) 520- and 550-series engines produced by TCM during a three-month period have suffered broken crankshafts. This alarming fact came to light last week when TCM's new Director of Field Sales and Service, Bill Blackwood, phoned 127 owners of new and remanufactured engines with crankshafts manufactured between March 11 and June 18, 1998, and asked them to have their crankshafts inspected at TCM's expense. TCM is asking each owner to have the #1 and #3 cylinders and connecting rods removed so that a dye-penetrant inspection of the crankshaft can be performed on the aft side of the #2 crankshaft cheek, where five of the six breaks have occurred. Additionally, TCM has issued Special Service Instruction SSI 99-1, which details the inspection procedure and the area to be inspected.

...Few Clues So Far As To Cause Or Scope...

So far, there are few clues to the cause of these breakages nor any obvious pattern to indicate which engines may be at risk. The six or seven known failures (the exact number depends on whom you talk to) appear to have occurred in both two- and three-bladed prop installations, both Hartzell and McCauley props, both sandcast (rear alternator) and permold (front alternator) engine configurations and on both new and rebuilt engines. All were the latest-style vacuum-arc remelt (VAR) crankshafts. Affected aircraft include a Mooney Ovation, a Piper Malibu, a Cessna T210, a Beech Baron, a Cessna 206/207, plus an IO-550 on an unidentified aircraft. Luckily, only one of the aircraft was damaged and there has been only one minor injury resulting from this problem to date. So far, the only real clue seems to be that the broken crankshafts were all manufactured between March 11 and June 18, 1998. Five of the six cranks broke on the aft side of the #2 cheek, and the breaks were almost identical in location and shape. The March 11 failure occurred on the #5 cheek, and it is not yet known whether it is related to the other five (or six). The breaks occurred at between 85 and 175 hours time-in-service.

...TCM Asking Owners For Help...

TCM is currently asking for inspection of other crankshafts manufactured on the same, previous or following day as each of the six failed cranks. Furthermore, they are presently concentrating on cranks with between 50 and 200 hours time-in-service. Depending on the results of these field inspections, TCM may well call for inspection of a wider range of crankshafts in the coming weeks. After arrangements are made to remove the cylinders and connecting rods, owners are asked to contact Blackwood on a special toll free phone number (888-200-7565) for coordination with a factory tech rep for inspection. TCM is paying for all parts and labor costs.

How can an owner tell if his crankshaft should be inspected? Each new crankshaft has a serial number consisting of seven or eight characters stamped or vibro-etched on the edge of the prop-mounting flange. The first character is a letter that denotes the month of manufacture (A for January, B for February, etc.). The next two digits denote the day of the month and the two digits after them denote the year. The last two digits are a sequence number for crankshafts manufactured that day and an "N" suffix is used to denote a nitrided crankshaft.

According to TCM, the manufacture dates of the known failures were March 11, May 11, May 12, May 13, June 10, June 17, and June 18, 1998. Since TCM wants to inspect all crankshafts manufactured on these dates plus one day earlier and one day later, the complete list of date codes to be inspected is: C1098xxx, C1198xxx, C1298xxx, E1098xxx, E1198xxx, E1298xxx, E1398xxx, E1498xxx, F0998xxx, F1098xxx, F1198xxx, F1698xxx, F1798xxx, F1898xxx, F1998xxx.

...What Owners Should Do Now

Owners of factory new or rebuilt TCM 520 or 550 engines manufactured since March 1998 and those who have field overhauled engines with new crankshafts of the same vintage should immediately check the crankshaft date code on the prop mounting flange to determine the manufacture date. If your crankshaft was manufactured between March and June of 1998, contact TCM's Bill Blackwood at 888-200-7565 for instructions. If your crank manufacture date falls outside that range, hang onto the date code in case TCM expands the scope of the inspections.

Monday, April 19, 1999

Teledyne Continental Will Order Massive Crankshaft Inspection

Affects All TCM 470-, 520- And 550-Series Cranks Built In 1998...

Teledyne Continental Motors (TCM) executives and engineers worked feverishly last week and through the weekend on a new mandatory Service Bulletin that will require some 2,200 nearly-new big-bore TCM engines to be opened up for ultrasonic inspection of their crankshafts. According to TCM's John Barton, Senior Director of Engineering, the order — to be known as Critical Service Bulletin 99-3 — will affect all new and factory-rebuilt 470-, 520- and 550-series engines with crankshafts manufactured between January 1 and December 31, 1998, as well as field-overhauled engines with the crankshafts installed. TCM says it expects to release CSB 99-3 this week, and a Priority Letter Airworthiness Directive ordering compliance is expected from the FAA next week. Owners of engines with the affected crankshafts will be required to have the #1 and #3 cylinders, pistons and connecting rods removed from the engine to expose the crankshaft. Both harmonic dampener counterweights will also have to be removed. An ultrasonic inspection of the #2 and #5 crankshaft cheeks must then be performed by designated TCM personnel. TCM says it will pay for the disassembly, inspection, and reassembly of the engines.

...A Classic Whodunnit...

It was late last year when TCM first became aware of crankshaft failures in seven of its 520- and 550-series engines of a type never seen before. Metallurgical analysis revealed these to be fatigue fractures in the #2 or #5 "long cheeks" near where the harmonic dampener counterweights are attached. What made these failures particularly surprising to TCM engineers was that the area of failure is a low-stress area of the crankshaft. Engineering calculations indicated that the area in question should have been subject to a maximum stress of only 23,000 PSI and that the crankshaft should have been able to withstand 120,000 PSI before failing. In fact, it appeared that the seven crankshafts that failed in this manner all had fractures that progressed nearly 90% of the way through the cheek before the crankshafts ultimately failed. TCM had seen crankshaft failures before but never in low-stress areas like this.

What could be causing this? TCM engineers were baffled. The only clue they had was an odd pattern in the manufacture dates of the seven broken crankshafts. The earliest one was manufactured in March 1998. Then there were three failures in cranks manufactured within a one-week period of May and three more in cranks manufactured during a one-week period in June. All seven crankshafts had very low time when they failed: between 85 and 175 hours in service. Six of the seven failed in the exact same spot on the #2 cheek, while the seventh failed in the corresponding location on the #5 cheek.

As AVweb reported last week, TCM responded by contacting 127 owners of new and factory-rebuilt engines with crankshafts manufactured within one day of the dates of the seven failed cranks. The owners were asked to remove the #1 and #2 cylinders so that a dye penetrant inspection of the #2 and #5 cheeks could be performed. TCM issued Special Service Instruction SSI 99-1 to describe the inspection procedure. Priority was given to engines that had between 50 and 200 hours. In all, some 54 crankshafts were inspected under SSI 99-1. Only one — in an IO-520 engine on a Beech Baron — showed any anomalies. Inspection of that Baron's engine revealed a tiny crack in the #2 check area precisely where most of the broken crankshafts had failed. This turned out to be the break that the TCM engineers needed to solve the puzzle.

The Baron engine was torn down and the crank analyzed in TCM's metallurgy lab. Although the crack seemed almost insignificant, it had breached the outer nitride "case" of the crankshaft (which is only .025" thick). The nitrided surface of these cranks is extremely hard and not easy to damage inadvertently. After eliminating various other possibilities, TCM engineering sleuths concluded that the damage must have been caused by a 5-ton hydraulic ram used to press counterweight bushings into the crankshafts during the final stages of manufacture. Factory records indicated that there had been some problems with the tooling used to do this and that the tooling had been repaired at one point during 1998 and finally replaced altogether in December. Apparently, concluded TCM, the troublesome tool had managed to nick the cheeks of some crankshafts during the bushing insertion process and it was those nicks that subsequently caused seven crankshafts to fracture.

...Assessing The Magnitude...

The seven crankshafts all failed in flight, six of them in single-engine airplanes. Fortunately, six of those aircraft were able to make on-airport landings, while the seventh landed off-airport but caused only minor injuries to the occupants. That's the good news. The bad news is that TCM has no way of knowing how many other crankshafts were damaged by the errant hydraulic ram. Based on the results of the SSI 99-1 inspection, it's likely that relatively few crankshafts were affected. In fact, it's entirely possible that all of the crankshafts that are ever going to fail from this problem have already failed. But with lives potentially at stake, neither TCM nor the FAA was willing to bet on it.

After intense discussions between TCM top management and the FAA's Atlanta MIDO which oversees TCM's Mobile, Ala., manufacturing operations, it was decided that every crankshaft that could conceivably have been damaged would have to be inspected. Although the seven cranks that failed were all from 520- and 550-series engines, the decision was made to include 470-series engines in the inspection program — including the O-470 engines that power the ubiquitous Cessna 182 — since those crankshafts were built using the suspect tooling. Furthermore, although all the failed cranks were manufactured in the second quarter of 1998, TCM decided to extend the scope of the inspection program to all 2,200 crankshafts manufactured during the entire year.

Although the preliminary fact-finding inspection of SSI 99-1 involved a simple dye penetrant inspection, TCM concluded that a more sensitive inspection method was needed to make certain that even the tiniest cheek fracture would be detected. The traditional method used to inspect crankshafts is magnetic particle inspection ("Magnaflux"), but it requires that the crankshaft be removed from the engine. TCM finally came up with an ultrasonic inspection technique that offers the desired sensitivity yet can be done without splitting the engine case. The downside of the ultrasonic inspection is that it's not the sort of thing that your friendly neighborhood A&P can do — it requires special and costly equipment and must be performed by a highly trained technician.

...What Happens Next?

Within the next few days, TCM plans to issue Critical Service Bulletin 99-3 that will identify all affected new and factory-rebuilt engines by serial number. It will also provide instructions for determining the crankshaft manufacture date from the date code stamped on the propeller-mounting flange for field-overhauled engines and for crankshafts in the inventories of distributors and overhaul shops. Under CSB 99-3, owners of affected engines will be required to have their engines prepared for inspection at a maintenance facility of their choice by removing the #1 and #3 cylinders, pistons, connecting rods and counterweights. Then, an ultrasonic inspection must be performed by a TCM-designated inspector. TCM will pay for the engine disassembly and reassembly and will provide the inspections without charge. According to Barton, TCM and the FAA will require that the inspection be done within the next 10 hours for engines with affected cranks that have 300 hours or less time in service. Engines that have accumulated more than 300 hours will probably have an extended compliance time, on the theory that if their cranks were going to fail, they would have done so by now.

The logistics of this inspection program are daunting. TCM's John Barton tells AVweb that the United States will be divided into eight regions, with one designated inspector assigned to each region, plus two "roaming" inspectors to handle special situations such as fleet operators. Plans for international logistics were still being formulated at deadline. The designated inspectors will be a combination of TCM employees and contractors from Law Engineering, an internationally-known firm specializing in non-destructive testing. The inspectors were undergoing training in Mobile last week and should be deployed to the field sometime this week. TCM has also established a special telephone center to facilitate the scheduling of these inspections. Owners, operators or maintenance facilities will be asked to call TCM toll-free at 1-888-200-7565 to provide information about their engines and to schedule a specific date and place for the ultrasonic inspection. TCM says it will also provide specific instructions and a copy of CSB 99-3 on the TCM-link web site.

One question remains unanswered: Is it possible for a relative handful of TCM-designated inspectors to inspect some 2,200 crankshafts within the constraints of a 10-hour compliance window without grounding a lot of airplanes for a painful amount of time? As we said earlier, the logistics are daunting.

NOTE: AVweb's coverage includes TCM's SSI 99-1. AVweb will also include CSB 99-3 as soon as it is available.

Monday, April 26, 1999

TCM Crank Issues Get Curiouser And Curiouser

Latest On TCM Crankshaft Inspections...

Early last week, Teledyne Continental Motors issued Critical Service Bulletin (CSB) 99-3 mandating ultrasonic inspection of all TCM 470-, 520- and 550-series crankshafts manufactured during 1998. The bulletin was basically as we described it to you last week, with a few new wrinkles. The biggest surprise was that the number of affected crankshafts has increased from 2,200 to more than 3,000 — mostly because TCM realized at the last moment that reconditioned crankshafts used in its rebuilt engines had to be included in the inspection program. Those cranks made the cut since they received new counterweight bushings installed by the same five-ton hydraulic ram that was implicated in the failure of seven new crankshafts. TCM set the compliance time at 10 hours for crankshafts with up to 300 hours time-in-service, and 25 hours for those with over 300 hours. At week's end, the FAA had issued Priority Letter Airworthiness Directive 99-09-17 to give the force of law to CSB 99-3.

...Will Be Costly For TCM, Painful For Owners

As AVweb reported last week, affected TCM engines will have to be prepped for inspection by having the #1 and #3 cylinders, pistons, connecting rods and counterweights removed from the engine to expose the crankshaft. A TCM-designated technician will then perform the ultrasonic crankshaft inspection, after which the engine must be reassembled. TCM will reimburse up to $700 for the disassembly and reassembly of normally aspirated engines — and up to $900 for turbocharged engines — and will provide the ultrasonic inspection itself at no charge. The big remaining unknown for owners is how long their airplanes will be out of commission awaiting inspection. Given that TCM presently has only ten designated inspectors to cover the entire United States, some quick arithmetic would suggest that it could take as much as six months to inspect the more than 3,000 affected engines. However, TCM's John Barton told AVweb that the company was working on a plan to recruit and train additional inspectors and to obtain more ultrasonic testing equipment for them to use. We'll keep you posted. Meantime, your best bet is probably to take your plane to a large metropolitan maintenance facility where lots of other airplanes are being similarly prepped for inspection, since it's a fair guess that those shops will have first priority on the TCM inspectors' itineraries. And be sure to complete the CSB 99-3 contact form online ASAP so you get on the inspection schedule ahead of those unenviable souls who don't read AVweb news.

NOTE: AVweb's coverage includes the full text of TCM CSB 99-3, in both HTML and PDF formats, plus a synopsis, FAQ, and a link to the CSB 99-3 online contact form.

Monday, May 3, 1999

TCM Crankshaft Update

Continental Moves To Expedite Inspections...

After a week of confusion, mixed signals and unreturned phone calls that had many affected owners hopping mad, Teledyne Continental Motors appears to be getting its act together with respect to the crankshaft inspections mandated by TCM Critical Service Bulletin 99-3 and FAA Airworthiness Directive 99-09-17. On Saturday, TCM told AVweb that it had doubled the number of trained ultrasonic inspection technicians assigned to the program — from 10 to 20 — with even more inspectors currently in training. The company also said that it was about to release regional inspection schedules advising when inspectors would be working for the next two weeks at designated FBOs around the country, enabling owners to expedite the inspection process by bringing their aircraft to the inspectors rather than waiting for the inspectors to come to them. The schedules will be updated weekly, with inspectors continuing to make the rounds of FBOs as necessary after the initial pass. In addition, TCM announced that it will conduct the CSB 99-3 inspections on a full-time basis at its facility in Fairhope, Ala. (4R4), and that it was considering other locations at which inspections would be conducted full-time.

...And Minimize Owner Pain

TCM also indicated that owners of factory new and rebuilt engines will receive a special warranty covering 100% of parts and labor for six months or 240 hours upon completion of CSB 99-3 requirements. For engines already covered by TCM warranty, the normal coverage will be superseded by the special warranty and resume after six months. TCM plans to mail details of the special warranty and inspection schedules to all owners who have contacted TCM to arrange CSB 99-3 inspections, as well as posting them at At press time, less than half of the 3,000 affected 470-, 520- and 550-series engines with crankshafts built in 1998 had been registered in TCM's contact database. Owners who have not yet done so are urged to call TCM toll-free at 1-888-200-7565 or to complete the online contact form at

Monday, May 10, 1999

TCM Getting Aggressive On Crankshaft Problems

More Inspectors Added To Tackle Large Workload...

As Teledyne Continental Motors continued to climb a steep learning curve associated with its field program to inspect 3,200 crankshafts, the company announced last week that they were hiring and training 20 additional inspectors to expedite the inspections. As many as 40 inspectors should be available to inspect the suspect crankshafts by late May, and TCM is now saying that the required inspection — which involves four specific areas of the crankshaft and is averaging 30 to 45 minutes per engine — can be accomplished more efficiently than originally thought. As reported by AVweb over the last several weeks, TCM discovered that faulty crankshafts could have been installed in new, factory-remanufactured, or field-overhauled 470-, 520- and 550-series engines produced in 1998. TCM has designated a number of service centers at FBOs across the country and has set a schedule for when inspectors will be at those sites. TCM is leasing aircraft to fly inspection teams to those sites for the scheduled ultrasonic inspections. Owners of affected aircraft can check the TCM web site or call TCM at 888-200-7565 to register and find the nearest designated inspection station.

...Of Urgent Engine Inspections...

According to the AD and TCM Critical Service Bulletin CSB99-3A, affected engines with 300 hours or less time-in-service can fly ten hours after operator receipt of the Priority Letter AD; planes with more than 300 hours TIS can fly 50 hours after receipt. The Cessna Pilots Association is recommending to its members that they may want to arrange to bring their own mechanic with tools to remove and replace the cylinders for the inspection, since some shops report that they can't accommodate all the pre-and post-inspection engine work with their own mechanics. With TCM allowing $700 to $900 for the pre- and post- inspection engine work, bringing a mechanic to the site could be the quickest way to complete the inspection. Still unknown is how crankshaft inspections will be handled for foreign owners of affected engines. TCM is only saying that inspections in foreign countries are presently in the planning stage and won't give any inspection dates. To help alleviate some of the aggravation suffered by owners, TCM also said they will issue a six-month/240-hours 100 percent Parts and Labor warranty to owners that are affected by this AD as appreciation for supporting the inspection process.

...But Inspections May Not Be Going Smoothly

TCM says that one inspector can check 10 or 12 engines per day under optimal circumstances. But the inspections aren't all going quite that smoothly: One AVweb reader reports that an inspector showed up at one Alaskan FBO two days behind schedule, inspected only 10 of the 17 prepared engines, then departed for his next scheduled location, leaving seven engines in limbo and owners climbing the walls. AVweb has asked TCM to comment on the reader's report. Meanwhile, TCM reports that the inspections to date have turned up no fatigue fractures but a significant number of potential problems, resulting in several dozen engines being returned to TCM headquarters in Mobile, Ala., for installation of new crankshafts and post-mortem metallurgical analysis of the "old" ones. TCM is promising to turn around these engines in approximately two weeks, which will undoubtedly have some impact on the availability of new and remanufactured engines for other customers — especially if the ultrasonic testing "failure rate" continues at the current level. Stay tuned to AVweb for reports on the latest developments in this evolving situation.

Monday, May 17, 1999

TCM Crankshaft Inspection Update

One Step Forward, One Step Back?

As Teledyne Continental Motors' efforts to inspect some 3,200 of its 470-, 520- and 550-series engines continued last week, a clearer picture emerged of the scope of the task facing TCM and how well the company was holding up. The answer? TCM is making an admirable effort to deal with the task it faces, but it sure looks like it's going to be a long, hot summer at company headquarters in Mobile, Ala.

Last week, AVweb reported on an abortive visit by a TCM inspector to an FBO in Palmer, Alaska, at which 17 engines were to be inspected. We told you that after looking at 10 of the 17, the inspector left, saying that he was late for his next appointment, leaving seven engines in limbo and their owners hopping mad. After our story, TCM phoned AVweb to express displeasure with the story, explaining that according to TCM tech rep Loren Lemen, the seven engines were not inspected because they had not been fully prepped for the inspection, leaving the TCM inspector little choice but to move on.

That's reasonable enough, but what about last Friday at Santa Maria, Calif. (SMX)? Located somewhat off the beaten path on the central California coast, SMX nonetheless serves as headquarters for the Cessna Pilots Association (CPA) and, coincidentally, is home base for AVweb Editor-in-Chief Mike Busch's Cessna T310. Well, Mike and CPA Executive Director John Frank showed up at Aero-West Specialties, the largest aircraft service facility at SMX, to see how the inspections were progressing, but the TCM inspector never showed. To make matters worse, nobody from TCM bothered to call the FBO to tell them that the inspector wouldn't be coming, leaving Aero-West owner Michael Lentini , several of his mechanics, three aircraft owners, Mike Busch and John Frank all twisting slowly in the wind. After numerous phone calls to Mobile, FBO owner Lentini was told that the designated TCM inspection team had encountered a lot more engines prepped for inspection at their preceding scheduled location than they'd been told to expect, and upon reporting this to Mobile, they were instructed to stay and finish them. Ultimately, a "Plan B" was negotiated, which called for the inspectors to show up at SMX on Sunday. The inspections of three engines took place Sunday morning — two of the three engines failed, incidentally — and AVweb's Mike Busch was there, camera and notepad in hand.

Despite the two-out-of-three failure rate at SMX, however, it appears that only about 10 percent of the engines inspected so far under CSB 99-3 have failed the ultrasonic testing procedure and are being shipped to Mobile for crankshaft replacement. We understand that nearly 100 engines have been earmarked for crank transplant so far, and that the TCM factory is running seven days a week, two shifts a day, to turn them around as quickly as possible. So far, the turnaround on engines returned to Mobile appears to be about three weeks, but there's no telling whether TCM can hold the line on that as the inspection program proceeds.

Needless to say, AVweb will continue to monitor and report on TCM's response to this daunting challenge. Meantime, look for Mike Busch's in-depth first-person report about the TCM crankshaft inspection process next week.