Firsthand Look: TCM Crankshaft Inspections

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SPECIAL REPORT. For the past month and a half, AVweb editor-in-chief Mike Busch has been living and breathing the ongoing saga of the crankshaft problems in big-bore Continental engines. He's been in nearly continuous contact with the TCM factory, talked to dozens of owners and FBOs (some furious, others happy), and watched over the shoulders of TCM inspectors when they came to his home airport to perform the ultrasonic testing mandated by Critical Service Bulletin 99-3. Here is Mike's firsthand report on the TCM crankshaft situation past, present and future.

ATIS"Hey, Mike! Looks like there may be a problem with Continental crankshafts."


I looked up from my Makita, with which I'd been reinstalling inspection plates at the end of a grueling month-long annual on my Cessna 310. It was Monday April 5th, if memory serves, and the voice from the open door at the top of the stairs leading down onto the hangar floor belonged to Steve Ells, technical representative and magazine editor for the Cessna Pilots Association (CPA). As owner of two big-bore Continentals, I gave Steve a look that told him that he had my undivided attention.

Steve went on to say that he'd received a phone call from a CPA member who said he'd just been contacted by TCM Director of Field Sales and Service, Bill Blackwood, and asked to remove two cylinders and connecting rods from the factory-rebuilt IO-520 engine on his Cessna 210 and have the aft side of the #2 crankshaft cheek inspected with dye penetrant. The owner was told that six low-time new and reman 520- and 550-series engines had suffered broken crankshafts, and that his crankshaft had been manufactured on the same day as one of the failed ones, causing TCM to ask that it be checked. As soon as the phone call from Blackwood ended, the owner called CPA for a second opinion on whether or not he should consent to TCM's unusual request.

Steve called a few engine shops to find out what they knew about these crankshaft failures, then called Blackwood to confirm that what the owner had told him was true. It was. Blackwood said that he'd phoned 127 owners of engines with crankshafts that had been manufactured within a day of the manufacture date of the six failed cranks — most of which had been built in May or June, 1998 — and asked that the owners submit to a voluntary inspection at TCM's expense.

Getting The Word Out

Crankshaft.
SSI 99-1 targeted 127 crankshafts for voluntary inspection, but we felt it likely that the scope of inspections would soon be expanded. But when the number jumped to 2,200 and then to 3,000, even we were surprised.

The next day, I had a quick informal conference with Steve and CPA executive director John Frank, and we all agreed that this was an important story that all owners of big-bore Continentals needed to know about. It was immediately apparent to us that unless TCM was able to find out quickly why the six cranks failed, they'd have no alternative but to widen the net and call for the inspection of more engines. They'd been very lucky so far: Only one of the six crankshaft failures had resulted in a crash, and that crash involved only minor injuries. But the next failure could prove fatal. TCM would have to move quickly.

Our job, as we saw it, was to get the word out to owners. On Thursday morning, April 8, CPA devoted most of its weekly CPA ATIS email newsletter to the TCM crankshaft situation. I decided to make this the lead story in AVweb NewsWire and AVflash which went out to 100,000 aviators in the wee hours of Monday morning, April 12. We advised all owners of Continental -520 and -550 engines with cranks manufactured in 1998 to check their propeller flanges for the manufacturer's date code, and to be prepared for TCM to expand the scope of the inspections. On Tuesday, we obtained a FedExed copy of TCM Special Service Instruction SSI 99-1 containing the full details of the dye penetrant inspection procedure. We immediately scanned and OCR'd it, converted it to HTML, and put it up on the Web. (TCM's own Web site didn't have a syllable about this yet.)

Things started happening at warp speed after that. By mid-week, we learned that TCM was pretty sure it had found the cause of the failures: a faulty tool mounted on a 5-ton hydraulic press that was used to install counterweight hanger bushings into the crankshafts. The bad news was that this tool had remained in use until late December, 1998. Clearly, the number of crankshafts that might have been compromised was going to be a whole lot more than 127.

TCM wings
TCM management — particularly Sr. Dir. of Engineering John Barton — was completely candid and refeshingly forthcoming about the problem. Clearly, TCM was as interested as we were in getting the word out to owners.

By week's end, I received word that TCM would be issuing a Critical Service Bulletin requiring inspection of all big-bore crankshafts manufactured during 1998, and that the FAA would follow suit with an Airworthiness Directive. On Saturday morning, I spent more than an hour on the phone with John Barton, TCM's Senior Director of Engineering, asking questions and taking notes on the scope and expected details of the upcoming CSB and AD. Barton was entirely candid and forthcoming with me — a refreshing surprise, given the obvious delicacy of the situation — and offered straight, detailed answers to all of my questions. It was obvious to me that he was as interested in getting the word out to owners as I was. Nobody wanted to see another in-flight crankshaft failure.

I worked feverishly through the weekend on a long, detailed lead news story for AVweb NewsWire and AVflash. By Monday morning, April 19, the aviation community learned about the details of CSB 99-3 days before TCM issued it. In addition to expanding the scope of inspections to a full year's worth of crankshaft production and adding 470-series engines, TCM had decided that dye penetrant inspection wasn't adequate, and would be calling for ultrasonic testing (UT) of the crankshafts — a procedure that required special test equipment and highly-trained non-destructive testing (NDT) technicians to perform.

This was turning into a very big deal indeed. Initial estimates were that 2,200 engines would have to be inspected. Later, TCM realized that reconditioned crankshafts used in reman engines would have to be included, too, since those were re-bushed using the same tooling that had caused the problem. By the time CSB 99-3 hit the streets at the end of the week, the number of affected engines had grown to more than 3,000. For those with less than 300 hours time-in-service — which was most of them — compliance time was just 10 hours.

Crisis Mode In Mobile

TCM staffer manning the CSB 99-3 toll-free hotline.
TCM set up a toll-free hotline to allow owners to register for inspections. Unfortunately, owners expected these folks to have all the answers. When they didn't, owners got frustrated.

Having ordered the inspections and offered to pay for them, TCM was now faced with a monumental logistics challenge. For one thing, they needed to find out where the 3,000 affected engines were located and who owned them...fast! The company rushed to set up a special toll-free telephone hotline (1-888-200-7565) staffed by personnel armed with a "CSB 99-3 Contact Form" and instructed to solicit all the pertinent information from each owner who called, and to enter the information into a computer database. They also put up an electronic version of the contact form on the TCMlink Web site. AVweb publicized both the number and the URL even before CSB 99-3 was officially released, and the calls and e-forms started pouring in.

Unfortunately, many owners who called the hotline came away frustrated. They were looking for answers about when and where their inspection could be accomplished and how soon they could get back into the air. The people at the other end of the phone didn't have any answers for them — no inspection plan or schedule yet existed — and all the hotline people could do was to take the owners' information and promise someone from TCM customer support would get back to them. In some cases, the owners were promised that they'd receive a callback within a few days, and when that didn't happen, the owners were understandably furious.

(Once upon a time, back when I was young and foolish, I used to take telephone messages for my wife by saying, "I'll have her call you back as soon as she returns." But, as I grew older and wiser, I learned to say, "I'll let her know you called." Never make promises you can't keep.)

Ultrasonic crankshaft inspection
With 3,000 engines to inspect and only ten NDT inspectors trained for the procedure, the near impossibility of the task started to become apparent to TCM management.

Meanwhile, in the TCM executive offices, top management was just coming to grips with the daunting task of getting all the inspections done in a reasonable amount of time. CSB 99-3 required that the UT be carried out by a Class III NDT technician who had gone through special training by TCM in the procedure. TCM had only a handful of suitably-qualified technicians in-house. They contracted with one of the world's largest NDT firms — Law Engineering, Inc. — to provide additional inspectors. But a week after CSB 99-3 was issued, TCM had only been able to come up with ten qualified and trained inspectors on such short notice. When they divided 3,000 engines by ten inspectors, and took into account that those inspectors would be spending at least half their time travelling around to where the engines were, the near impossibility of the task started to sink in. Until that point, TCM had been so preoccupied with figuring out what needed to be done that they hadn't had time to deal with the question of how to do it.

On April 26, just days after TCM issued CSB 99-3, AVweb News carried the following advice to owners:

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.

This advice proved to be spot-on. In the course of the next few weeks, I received numerous emails from AVweb subscribers who had followed our recommendation and gotten their engines inspected within a week or so. Most passed the UT and were back in the air in short order. Those that didn't at least had the benefit of having "first dibs" on the fast-dwindling supply of replacement crankshafts. In contrast, owners who were not tuned into the Internet for the most part remained clueless until weeks afterwards, when they received a mass-mailed notice from TCM alerting them to CSB 99-3.

TCM Comes To Town...Late

Santa Maria Airport mapFast forward to Friday, May 14.

This was the day that TCM had scheduled an inspector to come to my home airport of Santa Maria, Calif. (SMX), to inspect three engines at one of the local FBOs, Aero-West Specialties LLC. The three aircraft — two Beech Bonanzas (an F33 and an A36) and a Cessna 414A twin — were prepped and ready. The owner of the FBO — Michael Lentini — and his lead A&P/IA — Ron Martinson — were standing by in eager anticipation, as were the three aircraft owners. John Frank, executive director of the Cessna Pilots Association, was there to watch the goings on. And of course, I was there — armed with reporter's notepad and digital camera. After being totally immersed in reporting this situation for more than a month, there was no way I was going to miss the chance to see the CSB 99-3 inspection process in the flesh.

Guess what? The TCM inspector never showed up. To make matters worse, nobody from TCM bothered to call the FBO to tell them that the inspector wouldn't be coming! There we were — FBO personnel, aircraft owners and journalists — all twisting slowly in the wind, so to speak.

David Smith performs UT on Cessna 414A engine
Law Engineering NDT technician David Smith inspects Cessna 414A engine, as Aero-West's IA Ron Martinson watches.

After lunch, I listened while FBO owner Lentini made several increasingly frantic phone calls to Mobile to find out what was going on. Eventually, Lentini reached Bill Blackwood, who told him that the reason the inspector didn't arrive on-schedule was that when he got to his previous inspection location in Southern California, he discovered a lot more engines there prepped for inspection than he'd been told to expect by the scheduling folks in Mobile. According to Blackwood, a bunch of owners, noting TCM's published inspection schedule (and heeding AVweb's advice to go to a major metropolitan area shop), simply flew their airplanes in as unscheduled "walk-ins" and the inspector was instructed to stay and finish them all up. Lentini asked when he could expect the three engines to be inspected, and was told, "we'll try to have someone there Monday." Lentini said that was unacceptable, and eventually persuaded Blackwood to arrange for the inspections to be done on Sunday instead.

As promised, Ken Howard of TCM and David Smith of Law Engineering arrived at SMX on Saturday night, checked into the Airport Hilton, and were at Aero-West Specialties at 0830 Sunday morning. Smith, a Class III NDT technician, was to perform the actual UT procedure, while Howard would handle the paperwork and sign off the inspections on behalf of TCM. Howard had another purpose as well — as TCM's service rep for Australia, he had been tasked by TCM to set up the CSB 99-3 inspection program for the Pacific Rim, and this was part of his on-the-job training.

Damage area, Cessna 414A crankshaft
#2 bottom counterweight blade from TSIO-520-NB engine on a Cessna 414A, showing damage which flunked the ultrasonic testing.

By the time I arrived at Aero-West Specialties at 0900, they'd already completed inspecting the first engine — an IO-470 on the Beech F33 — and found no problems. They were just starting to inspect the right engine of the Cessna 414A, a TSIO-520-NB. Ken Howard shined a flashlight onto the #2 crankshaft cheek and muttered the Australian equivalent of "uh oh." Each of us took turns as Ken patiently showed us where to look. Sure enough, a mark was clearly visible dead-center on the corner of the cheek. Ken explained that the presence of a visible mark did not necessarily mean that the crankshaft was rejected. Only the UT — which would measure the depth of the damage — could determine that.

At this point, NDT tech David Smith took over. His first step was to recalibrate the ultrasonic test equipment, something that is done immediately before every test. To do this, he used a specially-prepared steel bar that had a calibrated .020-inch nick on one corner. (.020 is approximately the depth of the nitride-treated outer layer of the case-hardened crankshaft.) The UT box was adjusted so that the ultrasonic echo from the .020-inch nick occupied exactly 100% of the height of the unit's oscilloscope-like display screen. Then, a reference line was programmed into the unit at the 30% level, representing an indication of about .006 inches. That, Smith explained, was the prescribed go/no-go threshold for the CSB 99-3. An UT indication of 30% of more would cause the crankshaft to be deemed unairworthy.

UT clearly shows C414A crank flaw at 47%
Annotated UT display with inset of damaged crankshaft, showing how the visual inspection and UT results correspond. The horizontal axis of the UT display denotes position, while the vertical axis denotes the strength of ulstrasonic echoes. "A" corresponds to the UT probe location at the top of the crankshaft counterweight hanger blade; "B" corresponds to the damaged area; and "C" corresponds to the bottom of the hanger blade. The horizontal line shows the go/no-go limit of 30%. The damage indication ("B") measured 47%, far beyond the no-go limit.

Smith deftly manipulated the ultrasonic probe into position on the #2 cheek while he watched the UT readout, and the rest of us jockeyed for position to look at it over his shoulder. As the waveform stabilized, Smith muttered the North Carolina equivalent of "uh oh" as the reading settled down at 47% — a definite failing grade. Howard explained that this did not mean that the crankshaft was actually cracked. In fact, TCM has not found actual propagating fatigue cracks in any of the 1,000 crankshafts it has inspected so far under CSB 99-3. Nevertheless, the 47% UT indication revealed that the nitride case of the crankshaft had been damaged beyond the maximum acceptable limits established by TCM Engineering, and would have to be replaced.

Smith proceeded to test the other three locations on the crankshaft where damage could have occurred, and they all came up clean. But this was little consolation. The 414A's engine would have to be removed, crated up, and shipped to Mobile for a crankshaft transplant. After installing the new crank, TCM will run the engine in a test cell, then ship the engine back to the FBO for reinstallation in the aircraft Ken Howard estimated that turnaround time would be approximately three weeks. This process is not considered to be an overhaul or rebuild — it will appear in the engine logbook as a repair, and the engine will retain its time-in-service. However, TCM is providing a six-month warranty extension, so that for all intents and purposes, the engine's warranty will start over again from scratch.

Jinxed?

Damage on A36 Bonanza crank.
Damage on an IO-520 in an A36 Bonanza. Harder to see than the 414A damage, but it also flunked. Once again, the damaged occured on the #2 bottom counterweight blade. All four blades are inspected: #2 bottom, #2 top, #5 bottom, #5 top.

The group moved on to the third engine, an IO-520 in an A36 Bonanza. Once again, Ken pointed out an area of visible damage on the #2 cheek. While not nearly as easy to see as the damage on the twin Cessna's crank, it was readily identifiable now that we knew what we were looking for. David fired up the UT machine, and announced that this engine would have to go back to Mobile as well.

Shocked by the fact that two of the three crankshafts had flunked the UT exam, I asked Ken Howard whether this was typical. "Heavens no," he said. He showed me his personal inspection log for the past couple of weeks. Including the three just completed, his logs revealed 56 engines inspected and six flagged for return to Mobile — a failure rate of about 11%. This fell right into line with the 10% to 15% figures I'd been hearing from various sources.

Subsequently, on May 20th, John Barton furnished me with a hot-off-the-press copy of an interim CSB 99-3 status report that TCM had prepared at the request of the FAA:

David Smith UTs the A36 crankshaft
UT inspector David Smith inspects the A36 crank. It flunked.

"Since April 23, 1999, TCM has conducted CSB 99-3A inspections on approximately 1,000 crankshafts/engines, or approximately 27% of the engines subject to this CSB. Of those crankshafts/engines inspected, approximately 130 (13%), have generated UT inspection results that caused the crankshaft to be tagged for removal and further inspection and analysis. Although we have not yet been able to remove and perform a detailed inspection of each of these 130 crankshafts, visual inspection has not revealed any crankshafts in the failure process. In our opinion, the UT inspection has proven to be a very sensitive and well-applied inspection.

"TCM presently has 26 UT trained inspectors performing inspections and is now inspecting approximately 500 crankshafts per week. We are continuing to train additional inspectors and should have 40 inspectors trained and deployed within the next two weeks.

"We will of course immediately notify the FAA should there be any significant change in our procedures or the results obtained."

What Lies Ahead?

F33 crank passed, got logbook sticker from TCM
Yesss!!! The F33 Bonanza's IO-470  got a clean bill of health after undergoing UT. Ken Howard signed off this logbook sticker showing that the engine was in compliance with TCM CSB 99-3.

If this 13% flunk rate continues, it means that about 400 engines will ultimately get shipped to Mobile by the time the CSB 99-3 inspection program is over. Although I understand that the TCM factory is now running seven days a week, two shifts a day, to keep up with the additional workload, it seems pretty obvious to me that the disassembly, reassembly and testing of those engines are almost certain to consume most of the final assembly and test cell capacity of the factory for the next few months. Furthermore, the crankshaft replacements will consume the equivalent of nearly three months' worth of new crankshaft production.

The result is almost certain to be a critical shortage of new and factory rebuilt engines, as well as a shortage of replacement VAR crankshafts for field overhaul shops. Keep in mind that big bore TCM engines equipped with older airmelt crankshafts are required to change to a new VAR crank at major overhaul (or any other time the case is split).

FBO owner Michael Lentini, TCM rep Ken Howard
FBO owner Michael Lentini goes over the inspection paperwork and warranty claim forms with TCM tech rep Ken Howard (seated).

These second-order effects of CSB 99-3 are already being felt. For example, I spoke to an overhaul shop last week that had an IO-520 engine from a customer's Cessna 210 that had suffered a prop strike. The crankshaft had been damaged by the sudden stoppage, so the shop ordered a replacement crankshaft from TCM. While the new crankshaft was still in transit from the factory to overhaul shop, the shop received notice from TCM that the crank had a 1998 manufacture date and was being recalled. The shop phoned TCM to order yet another crankshaft for the C210 engine, and was told by the TCM sales representative to expect delivery "in about 120 days...I guess." So the aircraft owner — whose engine was not directly affected by CSB 99-3 — is looking at another four months of downtime. There have to be dozens, perhaps hundreds, of other owners in similar situations.

The anticipated shortage of VAR cranks and new engines is also bound to depress the market for used aircraft that have high-time Continental engines and non-VAR cranks, at least temporarily. I recently exchanged email with one prospective purchaser who passed up what would otherwise have been a good deal on a V-tail Bonanza with a run-out engine, in part because of anticipated problems getting a VAR crankshaft.

It's not just crankshafts that are in short supply, either. Remember the two engines that flunked inspection in Santa Maria on April 16? Well, it's a week later now and those engines are still not on their way to Mobile. Why? Because it seems that TCM has run out of shipping crates! Not surprising in the slightest, if you think about it. As usual, the chain is only as strong as its weakest link. From an owner's point of view, it doesn't really matter whether it's crankshafts, gasket sets or shipping crates that are unobtainable. The result is the same: AOG (airplane on ground).

Cylinders, rods and counterweights removed for inspection
Cylinders, connecting rods and counterweights removed for inspection. A new gasket set is required before they can be reinstalled on the engine.

Meantime, the owner of the F33 that passed the UT inspection still doesn't have his plane back, either. Turns out that TCM provided the FBO the incorrect gasket set, and when the FBO called Mobile to complain, they received another gasket set via overnight express...also the wrong kind! (The F33 has an older-style engine, and the newer-style gaskets don't fit.)

Trust me, folks. The situation is bound to get a lot worse before it starts getting any better. It's gonna be a long, hot summer.

The good news is that everyone at TCM seems to be going the extra mile to try to make things right, albeit under very difficult circumstances. With about one-third of the CSB 99-3 inspections done and two-thirds left to go, TCM customer support finally seems to be getting a handle on the scheduling and logistics of moving the inspectors around. The inspector force itself has grown from 10 to 26 — which helps a lot — and another 14 inspectors are due to come on stream soon, many of them slated for assignment to international regions. For customers outside the U.S., the inspection program is about to begin in earnest, and every indication is that the people involved in coordinating it (such as Ken Howard in the Pacific Rim) have learned a great deal from the mistakes made during the early weeks of the U.S. inspection effort, and are unlikely to repeat them overseas.

AVweb will continue to do everything possible to keep you informed as the inspections and crankshaft replacements continue, and with them the inevitable collateral problems. We urge owners to be as patient and understanding as possible until this ordeal is over and the affected aircraft are back in the air. There'll be plenty of time for finger pointing and Monday morning quarterbacking later.


For the historically minded among you, we've posted the first six weeks of AVweb NewsWire reports on the TCM crankshaft situation.