Waypoints

AOPA Pilot Editor in Chief Thomas B. Haines has flown dozens of models of piston and turbine airplanes.

With a constant flurry of airworthiness directives and service bulletins, aircraft owners almost fear going to the mailbox. A month never goes by without hearing from the FAA, your aircraft's manufacturer, or some component manufacturer about an AD, SB, or "mandatory" SB. Most of these don't apply to most airplanes. Typically, the issue will affect only a limited number of airplanes that have had some part or component replaced during a specific period of time, but everyone who might be affected or who might know someone who once gazed at such an airplane on a ramp gets the mail.

Many of the bulletins from these official sources seem like overkill, but in the end the FAA and the manufacturers do a good job of communicating with owners about issues affecting their aircraft.

But imagine learning via one of these very official-looking letters that your airplane is grounded until you replace the crankshaft — a weeks- to months-long endeavor. That's bad enough if you use your airplane for personal flights, but it can be devastating if yours is an airplane used for commerce.

A passel of recent ADs affecting the crankshafts and crankshaft-gear retaining bolts of high-powered Lycoming engines has crippled entire fleets of airplanes. Affected are airplanes such as the Piper Turbo Saratoga, Malibu Mirage, and Navajo; Aero Commander; Aerostar; Cessna 206; and Mooney TLS Bravo to name just a few of the models powered by Lycoming -540 engines.

The crankshaft AD affects about 900 aircraft with turbocharged engines of 300 horsepower or more. The bolt AD affects engines serviced as far back as 1996.

How can this happen?

Issues with the bolts were identified in 1998 after a number of failures. The bolt holds the crankshaft gear in place. That gear drives the magnetos and camshaft. Failure of the bolt causes a complete loss of power. Robinson Helicopter, which uses the O-540 in its R44 model, stopped using the zinc-plated bolts at that time, favoring instead the more rugged cadmium-plated bolts. Lycoming continued to allow the use of the zinc bolts in airplane engines until it issued an SB, and the FAA followed up with an AD this fall requiring replacement.

Lycoming identified a pattern of crankshaft failures early last year. Typically, in its entire fleet of engines, Lycoming will see only one or two crankshaft failures a year, says Michael D. Wolf, president of Lycoming. However, in August and September 2001, there were reports of 10 to 12 failures. An SB and then an AD were issued in February 2002 requiring that the cranks of a group of engines be inspected prior to further flight. However, in August 2002 a Malibu Mirage crashed because of a crankshaft failure. Its engine was not among the original suspect group of engines. An emergency AD broadened the number of engines affected.

In the end, Lycoming identified a change in manufacturing processes that is thought to have caused some cranks in highly stressed applications, such as the turbocharged engines, to break.

According to Wolf, the company switched a few years ago to a hammer-forging process to make the cranks for the larger engines. The change was made because of the smaller volume of those engines manufactured relative to the number of lower-horsepower engines. Cranks for the larger volume of smaller engines continued to be manufactured using the press-forging process. After much investigation by the FAA and Lycoming, it was discovered that the greater heat generated during the hammer-forging process can cause the metal in the cranks to develop a honeycomb structure, weakening the metal and causing it to fail when highly stressed. Nonturbocharged engines are not affected because they don't place as much stress on the crankshaft as turbocharged engines.

To fix the issue, Lycoming has directed the subcontractor that manufactures the cranks to switch to the press-forging process for all cranks. Heat can be more easily controlled when using press forging.

Some batches of cranks are affected more than others, causing some airplanes to be grounded until the cranks can be replaced. Others can continue flying for up to 50 hours until their cranks can be inspected. Lycoming has developed an inspection method for those aircraft that involves removing the propeller and taking six tiny samples of metal for analysis from the tip of the crankshaft. The airplane is grounded when the test is done until the results are back. If deemed safe, the airplane can return to service. Otherwise, it is grounded until the crank can be replaced.

Back in business

After much analysis of the manufacturing process and greater quality control, Lycoming's subcontractor manufactured 50 crankshaft forgings last fall. They were cut up and analyzed. All of them passed the scrutiny, says Wolf. The subcontractor has since made 1,000 crank forgings. Lycoming is currently milling the forgings into serviceable cranks. Installation of new cranks was set to begin in January. Wolf hopes to complete all of the replacements by early in the second quarter of this year.

Each crank now comes with an extra piece of metal on the end. After manufacturing, the tip is cut off and analyzed. In addition, each of the crankshafts now undergoes an analysis by an electron microscope.

In the meantime, Lycoming is offering affected owners payment for alternative transportation and for storage of an aircraft grounded away from home. Those who sign an agreement not to take legal action against Lycoming also can receive weekly payments of about $100 to $200 toward additional expenses, such as aircraft finance payments.

To qualify for the transportation reimbursement, the owners must show that the trip is one that would have normally been taken in their aircraft. About 70 percent of customers are using the "customer care program," Wolf reports.

He is obviously frustrated that the situation occurred and that it has taken as long as it has to get owners flying again. "Safety is paramount," he says. "We're probably overly aggressive from a safety standpoint with the groundings, but it's the right thing to do. And so is our customer care program. It's expensive and I don't know of any such program that has been as far-reaching as this one. Our focus has been, 'How do we get through this with minimal customer impact and make customers feel good at the end about what Lycoming did for them?' It's not perfect, but we feel good about what we're doing."

And most customers understand. "They're generally dealing with it pretty well. Certainly, some people are not as understanding."

Will it happen again?

The FAA has stepped up its oversight of Lycoming as a result of the problems. Wolf has described the oversight as "tough but fair."

Lycoming made the change in the manufacturing process that led to the crank problem only after much analysis. It obviously didn't believe that the change would lead to a problem. The change was only one of many made by Lycoming and other manufacturers in recent years, as they have attempted to scale their processes to the current GA marketplace. Lycoming once built almost all engine parts at its plant in Williamsport, Pennsylvania. Now most component manufacturing is outsourced — not an uncommon practice in any industry.

This $40 million problem for Lycoming and major inconvenience for some of its customers show what can happen if such changes aren't investigated thoroughly enough prior to implementation. Economics will force manufacturers to continue to explore new ways of building components, so it's not an issue that is going to go away. The FAA needs to be willing and able to respond to such changes, providing the manufacturers with the flexibility they need but still assuring a safe product. Not an easy assignment, but something to contemplate as you drone along through rough weather or over hostile terrain.

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