Resource Spotlight: Flying Past TBO and Other Benefits of a Maintenance Management System

Imagine someone told your flying club that you didn’t need to overhaul your plane’s engine at 2,000 hours when it reached it’s TBO, and that you could safely keep flying behind that engine until 5,000 hours. You’d probably listen pretty carefully at what they had to say. After all, if you didn’t have to overhaul your engine, the club could save a lot of money and avoid the disruption to your members of having a plane in the shop for months.

Well, that is exactly what happened when Savvy Aviation recommended that Civil Aviation, Inc.—a flying club based in Milwaukee, Wisconsin—hold off on overhauling its Cessna 172’s engine when it reached its 2,000-hour TBO during the pandemic. 

“They were talking to us about whether they should overhaul it or replace it with a factory rebuilt engine,” Savvy Aviation Founder and CEO Mike Busch said. “The lead time for engines at that point was 10 or 11 months. We convinced them not to do any of those things and they took the engine to 5,000 hours. You can imagine how much money they saved by not euthanizing it at 2,000 hours.”

Savvy Aviation offers maintenance management and consulting services to aircraft owners, which includes flying clubs and flight schools. It doesn’t operate a shop perform maintenance. What it does do is a lot of analytical work. “We mostly do the headwork stuff that many shops are not very good at doing.”

Philosophy and Techniques

“We’re very strong believers in on-condition maintenance. We hate to see engines torn down before their time,” Mike said. “When it comes to TBO, flying clubs and flight schools are the poster children for continuing beyond TBO because their airplanes typically fly a lot.”

Many clubs are operating aircraft with small Lycoming engines. “If they fly regularly and aren’t allowed to corrode, they will frequently get to 4,000 or 5,000 hours without having any problems,” Mike said. 

The problem is that too many engines are torn down based on TBO, which Mike thinks is a fundamentally flawed concept. He does acknowledge there are a lot of owner-flown airplanes that aren’t going to make it to TBO because they don’t fly enough.

“We don’t believe in doing things at fixed intervals but doing things on condition,” Mike said. “If you think about how we maintain our automobiles, no one says, ‘I’ve got 100,000 miles I’m going to change the engine.’ That’s just crazy. But aviation has had this crazy concept for a long time, and it makes absolutely no sense.”

Most engines don’t wear out with time but require overhauls because of corrosion to the cams and lifters as a result of not flying enough, something not reflected in TBO, Mike said. That is why flying club and flight school aircraft have the greatest chance of going beyond TBO.

Other factors that affect engine condition include environmental risks. An aircraft in a humid climate is at greater risk of corrosion than an aircraft based in an arid climate, and aircraft tied down outside are a greater risk than those that are hangered.

Because they make maintenance decisions based on condition not time, Savvy is “very obsessive and compulsive about condition monitoring,” Mike said. “We’re very big on borescope inspections, engine monitor data analysis, and oil analysis. We don’t put much faith in the compression test because it is not a reliable indication of cylinder health.” 

If cylinders and heads are scoped regularly, there is a good chance of identifying exhaust valve problems before the valve has warped or experienced a lot of metal erosion. If you rely solely on the compression test, you might not catch it. “We strongly believe that the gold standard for determining cylinder condition is the borescope inspection,” Mike said. “The compression test is a relic of WWII.”

Savvy has developed a technique to remediate exhaust valve problems without dropping the exhaust system or removing cylinders if the problem is caught early enough. They’ve also had a lot of success using something called the solvent ring wash procedure for cylinders that have started to develop high oil consumption. If it is caught in time, you can often resolve the problem without the cylinder coming off.

“We’ve been on a campaign to introduce some of these new, better techniques both in terms of condition monitoring and in terms of remediating problems in less invasive and labor-intensive ways than the traditional ways of doing it,” Mike said.

For example, Savvy has found that about half the time a shop says that a cylinder must be replaced because of a head crack, there really isn’t a crack at all but just an artifact of the head casting. To avoid unnecessary cylinder replacement, Savvy will ask the shop to do a dye-penetrant test to verify whether the alleged crack is really a crack, and often the results confirm what appears to be a crack, actually isn’t.

Like engines, Mike believes condition inspections make more sense for propellers than overhauling on the basis of time. “In 50 years of looking at NTSB accident reports, I have yet to see a single general aviation accident that was attributed to an over-TBO propeller,” Mike said. “It just doesn’t happen. Sometimes they start to corrode. Sometimes they leak. Sometimes they don’t maintain constant RPM. All of those things are valid reasons to pull a prop off and send it to a prop shop. But if the thing is working, there is no reason to mess with it.”

Although engine manufacturers are required to publish a TBO as part of the certification, Part 91 operators are not required to comply with it. Most mechanics feel obligated to maintain an airplane according to the maintenance manual or “they think they are opening themselves up for potential liability if something goes wrong,” Mike said. “If you maintain an airplane according to the maintenance manual, it will be grossly over-maintained.”

What happens is mechanics are making maintenance decisions driven by fear of liability. So, what Savvy does is try to relieve that fear by working with the owner to make the decision about what maintenance is done, relieving the shop from having to make those decisions. “We’re not going to ask the shop to make the decisions about what maintenance should be done and what maintenance can be deferred. The shop’s responsibility is to do the maintenance that they are asked to do and do it competently,” Mike said. 

Savvy will respect a shops airworthiness determination but will often question how and why decisions are being made. One of the biggest challenges Savvy faces is when a shop does an annual is to have them simply inspect the aircraft and report what they find before they start ordering parts or fixing anything.

“If discipline isn’t imposed on them, shops tend to get into this inspect a little, fix a little routine. The get into a lather-rinse-repeat mode where they inspect the airplane, they see something wrong, they fix it,” Mike said. “That never gives the owner the opportunity to get into the decision loop, which is what results in surprises at invoice time and disputes between owners and shops.”

Savvy’s team will review a maintenance shops findings, go over it in detail with the aircraft owner, and make recommendations on how to address any discrepancies. Once the owner has determined what they want the shop to do, Savvy’s staff will provide the direction to the shop.

Savvy’s Services

Mike spent about 10 years teaching seminars for aircraft owners on how to manage the maintenance of their aircraft. “My mission was to make aircraft owners smarter when it came to maintenance and more actively involved in making the maintenance decisions rather than abdicating that responsibility to their mechanics,” he said. “I came to the conclusion that even when aircraft owners are highly educated in this area, they frequently lack the courage to give direction to their mechanics and to say no to things.”

So, 15 years ago, he started Savvy Aviation with a single service, which today is called SavvyMX. Over the years the company has diversified and now offer six different services—including a Pre-Buy program and a Breakdown Assistance service, which the company describes as “AAA for GA.”

With Savvy MX, clients are assigned one of Savvy’s 30 account managers, who are all seasoned A&P/IAs with at least 20 years of general aviation maintenance experience. They represent the aircraft owner in their transactions with shops and mechanics. It’s similar to hiring a lawyer, CPA, or a realtor to represent your interests. The service costs $750 annually for a single-engine piston aircraft.

“The dialogue with the shop becomes an IA-to-IA dialogue,” Mike said. “The shops and mechanics we deal with are much more likely to take direction from us then they are to take direction from the aircraft owner who they don’t treat as being equal in terms of maintenance knowledge. It’s a lot easier for us to say no to a shop than it is for the owner to say no to the shop.”

For owners that want the kind of maintenance advice that Savvy can offer but prefer to work with the shop themselves, Savvy offers a consulting service called SavvyQA. The biggest difference between the two services is QA is half the price at $375 a year, and Mike’s team works only with the aircraft owner for QA clients, but not directly with the shop like they do for MX clients.

Another difference is that SavvyMX service is more proactive. “We’re more reactive with SavvyQA,” Mike said. “We’re really responding to the aircraft owners who come to us an ask us for advice on stuff, but we don’t typically reach out to them. They reach out to us in Savvy QA.” 

For clubs, flight schools, or individual owners only interested in analytics, Savvy Analysis Pro is an engine monitor data analysis program. It can help spot problems such as magneto timing, clogged fuel injectors, failing CHT and EGT probes, and issues with powerplant management, to name a few. The program includes Failing Exhaust Valve Analytics (FEVA), which is a service Savvy developed that can identify the risk of a failing exhaust valve before it happens.

“We’re pretty much the only company that does analysis of digital engine monitor data,” Mike said. “We’re doing some really exciting stuff with AI and machine learning.”

In addition, Savvy offers a free analytics service in which an owner can input engine monitor data and use the online tools to do a self-analysis. The company also manages a lot of pre-buy inspections and has a 24/7 breakdown assistance service with a toll-free hotline that subscribers can call anytime day or night if they are stuck somewhere. Within 5 or 10 minutes they’ll have an IA on the phone, working with the pilot to help diagnose the problem to get them back in the air as quickly as possible.

Savvy has many flying clubs as clients, including the TSS Flying Club based in Gaithersburg, Maryland. You can read about their experience with Savvy in this month’s Club Spotlight.

Savvy prides itself on providing data driven analysis to aircraft owners, like flying clubs, to make condition-based decisions on maintenance, rather than decisions based on time. This methodology can save a flying club lots of money and downtime, and improve the safety and reliability of club aircraft.

“Flying club airplanes have an excellent chance of going the distance.,” Mike said. “I don’t think the Civil Aviation flying club in Wisconsin would have had the courage to take their 172 to 5,000 hours if we weren’t there to encourage them and coach them along. That’s all it took was a little courage.”

For more on flying clubs taking their aircraft beyond TBO, see this month’s Question of the Month

Related Articles