The Fuzzy Math of Airframe Maintenance

There are several costs associated with operating a jet aircraft. These costs come in a variety of categories, however, the predominant two categories are fixed and variable. Fixed costs include cost of aircraft (payment), crew, hangar, and insurance, which are annual costs whether you fly the aircraft or not.

What are variable costs and why are they different?

The variable costs are directly consumed or accrued while operating an aircraft.

The most obvious of these, is the cost of jet fuel which is ordered, paid for, and used on every flight.

However, there are two other major variable expenses which are not paid for as consumed…engine reserves and airframe maintenance. These are often referred to as deferred costs, although these costs are a significant part of every aircraft’s operating budget. In many cases, they are often overlooked exactly because they are deferred.

In this blog we are going to review only the airframe costs, since they come at a much higher velocity than do engine costs do. We will leave the engines to another blog.

How does airframe maintenance work?

The FAA requires all flight hours to be recorded, usually on the aircraft’s Hobbs meter. The Hobbs meter records hours of flight time like a car’s odometer records distance traveled.

The FAA requires, at predetermined intervals, either time (recorded hours) or calendar (annual or number of years) routine maintenance to be completed on the airframe. When the required airframe maintenance is accomplished the airframe maintenance is no longer deferred and must be paid, ideally from reserve accounts put aside for the deferred airframe maintenance.

This maintenance is not an option. It is a hard and fast requirement. The aircraft is no longer airworthy until the required maintenance is completed. Aircraft maintenance will vary by models, regarding hours and calendar requirements, so you need to know your specific requirements.

We can now see that airframe maintenance is one of the big operating costs that must be complied with, and paid for. So where does fuzzy math come in?

Here is an example of the fuzzy math.

To make the math easy to understand; we will use 100 hours of flight time as the interval between inspections. So, when an aircraft approaches 100 hours since its last inspection, it will be scheduled into a certified repair facility for that inspection.

Usually, this is where things can start to go wrong and the fuzzy math sets in. To begin, each type of aircraft has an approximate number of maintenance man hours for each hour of flight. To keep this simple again, let’s say your aircraft requires 3 hours of labor for every hour of flight. Simple math tells us there should be 300 hours of work performed at every 100 hour inspection on this particular aircraft. A maintenance shop will then give you a quote of the cost for this inspection. For example, the bid is for $20,000 plus parts and any discrepancies found during the inspection. At that point, a rational person is thinking, “OKay. I guess that means $30,000 plus or minus for the inspection.” However, what you can expect, and what you get are hardly ever the same thing.

The final charge for the inspection will usually be a total greater than $55,000.

So where did the $55,000 come from? Well they found “stuff”. The “stuff” they found is spelled out in pages and pages of what appears to be Sumerian…never before decoded hieroglyphics. Here is how it works.

Most often, once the aircraft goes into the hangar on Monday morning the shop assigns two men to go to work on the aircraft. The Shop will tell you to come back to pick up your aircraft on Thursday night. That is exactly what most pilots do…they leave the plane and come back 4 or 5 days later to pick up the aircraft. However, it should be noted that is not always the case, some crews do stay and follow what is going on, but in the end it makes no difference to the outcome.

So, going back to simple math…Two men working 16 hours (double shift) equals 128 man hours at $95 an hour. What happened to the 300 man hours? There are now 172 hours not accounted for, plus you are presented a $55,000 bill that is $25,000 more than you were expecting…and that is if you are lucky, and there were not any serious issues found. This bill is then explained in pages and pages of maintenance hieroglyphics that no one understands (including the maintenance shop in many cases).

At this point it is very apparent there is money being spent that is not clearly represented. (Remember the Sumerian never before decoded hieroglyphics, well there you go). Of course you can demand a clearer explanation and you will get an explanation. How clear it will be, or if it is to your satisfaction, is an unknown. Every case is different. But there is one known condition that is absolute. You will pay the bill, and here is why.

If the maintenance facility is not paid, your aircraft will not be released, and even if you got the plane out of the hangar, it would not now, or ever again, be legal to fly without the facility’s signing off in the aircraft’s log book for the inspection and the work that was accomplished. Freely translated, you no longer have any insurance and are violating about ten federal laws if you fly the aircraft. That is the maintenance version of a Catch 22.

For the sake of good will, the maintenance facility will spend a few hours going over their hieroglyphics with you, and then they will make an accommodation to you by taking $5,000 off the bill. Your choice is, take it or leave it. Of course everyone always takes it.

What is going on here, is what happens to the average aircraft that belongs to the single aircraft owner.

This is the old corporate aviation “two step”! It is an old song and it is played in many venues from airframe to engines, to parts and training.

What can you do to overcome this problem? Hire qualified personnel to oversee the entire project and protect your investment. Most pilots are not A&P mechanics and have no more idea of what the shop is doing that anyone else. If you are a big flight department with mechanics, send them along with the airplane, but even that is no assurance you are not going to run into the corporate aviation two step.

Erudite Solutions for Business Aviation


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