As an aircraft owner, you’ve experienced dealing with maintenance providers. You’ve read articles from several sources, including CPA, about how to manage maintenance events. But, you may not have a good understanding of what the maintenance event looks like from the shop’s side of the work order. A better understanding will help make reality more closely fit your expectations.

If you’re self-employed in some small business in a very small market with minimal profit margins and very high risk, you might have a pretty good idea of the small shop’s mind set. Mechanics have very valid reasons for doing what they do: finances, paranoia, responsibility, liability, and loyalty, amongst others.


For me, one of the most difficult parts of owning a busy aircraft maintenance shop is scheduling.  I manage the maintenance of about fifty airplanes around the country, and I find that other shops are in the same boat. The reward for being a good shop is lots of return customers. The burden of scheduling at a good shop is lots of return customers.

When airplanes arrive for schedule service, it’s rare that all their discrepancies are known. It’s not uncommon for a simple oil change to turn into a much larger job because a visible crack was noted in the exhaust system. The two hour oil change now becomes a search for the part and much more labor to R&R (remove and replace) the components. Not any of this extra time could be anticipated nor did the shop schedule for it.  So what happens to the other customer who was scheduled for after this oil change? Do we tell them to wait while the unexpected exhaust problem is dealt with on the first customer, or does the first plane get shuffled to the end of the line? Keep in mind, the end of the line is two months in the future.

Of course, no mechanic can ground your airplane, nor can an IA.  If you see the exhaust crack, or whatever might have been noticed during the oil change, and decide you still want to take the plane, the mechanic has no authority to ground you. He/she simply signs off the oil change and sends you on your way. I’m not saying you should do this, just making sure you understand your options and know the mechanic will note the exhaust crack in the shop records to protect himself.

Let’s expand the scenario to a group of planes scheduled for annual inspections. Say there’s three mechanics working in the shop, which gives us 120 man hours per week. An annual inspection on a typical, large, single engine Cessna might flat rate at 30 man hours. This means that at Fantasy Airport we could schedule 4 annuals per week.

In our scenario, let’s also say that the scheduled planes are a 1970 T210, 2008 Corvalis, a ‘68 U206, and a ‘76 177RG. What do you suppose the chances are that any of these planes will come out of the inspection with absolutely no discrepancies? So we’ve filled up this week with just the known inspections, but how much time should we have scheduled for the unknown repairs?  Keep in mind,  we have many other customers that want to plan the start date for their inspections as well.

A typical T210 might have thirty hours of repairs, a Corvalis about fifteen, a U206 about twenty, and a 177RG about fifteen. Then there’s the possibility that some surprises are found during the inspections. The 210 has a crack in the nose gear lower trunnion for at least another sixteen man hours, the Corvalis is found to have cracks in the aft floor structure for another twenty man hours, the U206 has corrosion on the forward cabin side skin for twenty-six man hours, and the poor Cardinal has a fuel leak at the drain valve with internal tank corrosion for another thirty man hours. The 80 hours anticipated quickly expands to another 90+ man hours.

As you can imagine, anything on the shop’s schedule next week gets toasted and much of the week after. But, if too much time is scheduled for unknowns, the mechanics have nothing to do and the shop loses money. It’s a constant battle to keep everyone in the shop working without delaying the customers’ completion expectations too much.

Man/Woman Power

I’ve heard some talk lately about the upcoming commercial pilot shortage. There’s a much smaller conversation taking place about a mechanic shortage. It doesn’t appear the airlines and large freight operators are having too much trouble in this regard, but the general aviation shops are. The smaller the shop, and the smaller the planes they work on, the worse the situation. I believe this small piston engine airplane mechanic shortage has several causes.

For one thing, Momma doesn’t really want Jr. to be a small plane mechanic. The idea of saying one works on big jets just massages the ego too much. When I put out ads in all the appropriate trade papers, aviation periodicals, and job search websites, I usually get no more than three viable applications. Upon contacting them, at least two will laugh at the idea of living in a town the size of ours. Most shops aren’t in the big cities, so this is a common theme in the industry.

Schools that provide formal training for mechanics operate on the path of least resistance. By that I mean they must provide at least the minimum training required by the FAA at a price that is profitable to the school and affordable to the student. All graduates exit with the same training and no specialization, as that is left to the first employer.

While veteran ex-military or long time airline jet mechanics are highly trained and skilled in their craft, they may be ill equipped to work on your Cessna 182. It’s not that small planes are more difficult, they’re just totally different. Twenty years of exemplary work on F4 Phantoms and C130s hardly prepares one for timing a magneto or borescoping a cylinder.

You should also be aware that many, if not most, mechanics are not aviation enthusiasts. At least not the way you are. Most mechanics only attend training seminars when required by the FAA or paid for by their employer. They’re not spending hours reading on-line mechanic forums and keeping up with the latest troubleshooting techniques.  Happily, there are exceptions to the rule and those are the guys/gals you want to find.

Technical Data

Piston aircraft, especially the legacy series, have minimal service manuals. The mechanic is expected to have some idea what is standard practice for the industry. In the Jet-A world, civil and military, the manuals are far more sophisticated and leave as little as possible to the imagination of the mechanic.

Your shop/mechanic is required to have the proper service manual on hand whenever performing work on a plane. These are not inexpensive, and he/she must have manuals for all the planes worked on. Consider that a shop which only works on single engine Cessnas would need manuals for about 19 different models plus multiple model-year variations for each. This alone is a huge expense.

I’m not an old guy, yet, but I’m older than most of the tech support folks at Cessna and have been working on these planes longer than some have been employed by Cessna. They do a great job with what they know and will make every effort to solve any problem. I’ve found them very knowledgeable on anything built under their watch. Unfortunately, some problems need the antiquated knowledge of the folks that put these legacy planes together 30+ years ago. While the tech guys at Cessna will go to the extreme to help out, sometimes the needed information just wasn’t well documented back in the day.

Some problems will take time to resolve, especially on older legacy planes. Phone calls go back and forth, messages are left, emails sent, and time passes. Eventually, the problem is resolved, so now the correct part can be searched for and purchased. Finally, weeks later, the replacement part is offered up for service, and your 1962 172 can take off.

Profit Margins

The cost of parts fills most complaints.  I won’t defend or attempt to explain why manufacturers charge what they do, but I can shed some light on how a shop thinks. To find the correct part needed for any particular job, an illustrated parts manual is needed. Actually, several manuals may be needed for a plane: the airframe manufacturer’s manual, then the engine manufacturer, and often other manuals for accessories like wheels, brakes, magnetos, etc. A shop depends on the profit from the parts in order to pay for these manuals.

Here’s a little insider information to price mark-ups on parts.  On most Cessna parts, the difference between a shops cost and Cessna’s list price is in the 25% range. A big margin would be 40% and many items have no markup margin at all. Some items, like batteries and spark plugs, have wild markups. A Gill G35 battery like one might find in most  legacy 12 volt Cessna shows a Gill manufacturer suggested list price of  $372.15. You can easily find one at a retail parts supply house for $180.00. The price you find online for these common parts is about the same price your shop will pay if they purchased from Cessna.

So you want to buy your own parts and save some money? Well, some restaurants allow patrons to bring their own eggs to the restaurant, so to speak. That’s great, but your mechanic may not be too happy about spending all that money for the manuals and the labor of researching part numbers; then for him/her to discover you bought the part at a slightly cheaper amount.  If you want to buy your own parts, get a manual and do the research so your shop doesn’t have to.

Shop Overhead

Overhead costs vs billing rates are an interesting ratio for aircraft service facilities. Let’s look at a different service provider for a moment. A licensed plumber may only need a truck that is filled with the tools and many of the common parts needed to follow his trade. The overhead for your airplane mechanic includes the building he/she occupies on the high rent district of the airport. All the typical utilities apply except air conditioning in the hangar. Then there is the manufacturer’s technical data that the shop is required to have. He/she must also have access to some sort of software for FAA AD research. There will be special jacks for low wing and high wing airplanes plus a multitude of other special tools.

If the shop is a Cessna authorized single engine service station, then a minimum inventory must be maintained that runs about $10,000.00. There is a fair amount of business and technical training required by Cessna which involves a good deal of time. A minimum amount of insurance that starts in the neighborhood of $10,000.00 per year is a must.   Cessna wants to ensure any shop bearing their name is properly equipped with the needed tools, knowledge, skill, and has product on hand to take care of customer’s needs in the best way possible.

Plumber labor rates are usually about 10% to 20% higher than what your small aircraft maintenance shop will charge. If anyone is making big money in the aviation industry, I assure you it’s not the general aviation mechanic.  Certainly, the plumber’s liability exposure is a fraction of the airplane mechanic’s. You can probably think of several other service trades that would fit into the same description.


In today’s litigious world many shops are pressured to recommend the maximum maintenance. By that I mean they will often push you towards the repair solution that puts the shop at the least possible risk.

We used to do a great deal of cylinder work in house, but the profit vs risk is such that it just doesn’t work anymore. Cylinders are sent out to a shop that specializes in that area. This means more down time and cost for the aircraft owner.

At the end of the inspection phase of an annual inspection, the shop might provide the owner with a long list of recommended service bulletins and other non-airworthiness related repair work. It then falls to the owner to determine what is worthwhile and what is just fluff. This will require a great deal of research on your part to make the best decisions.

If your mechanic suggests doing anything less than everything, he/she is exposed to great liability.  If everything is recommended, and you decide to decline or defer the unnecessary work, then you’ve let the mechanic off the hook. The mechanic fulfills his/her obligation and you fulfill yours.

Take Home

I spent my first career managing avionics shops for about five years. I then moved home to operate the family business specializing in airframe structural repairs. I soon purchased the business from my dad and began the slow process of making it my own. Over these last thirty years I’ve learned a lot about business relationships with customers. As with any relationship, there are always at least two sides to a story, and all could be true or all false. I’ve also learned that either view may be burdened by unfounded preconceived ideas and unrealistic expectations. Great expectations are…well, great. Informed expectations are even better.