Aviation Maintenance

Birthday Fun

My birthday fun….trying to balance and match engine parameters at 3:00 AM in the blowing snow and cold. Yeeha.

Im actually surprised i got a focused pic. The plane bucks around a lot when your holding the brakes….and it reeearaaalreally wants to go flying!IMG_2649As you can see here im almost done. Tweak the RH turbine up to 95%. Tweak the LH prop speed down to 1700 even, which will have a secondary effect of increasing the LH torque up. Then they will be beautifully matched.

Aviation Maintenance

And you thought your car was expensive…

The true cost of aviation is absurd. And I don’t think the general public is aware of this fact. FLYING IS EXPENSIVE. All too often I hear people complaining about how the prices have gone up, now they charge for landing fees, now they charge extra for baggage, there are no peanuts anymore, the in-flight meal was sub standard. On and on the list goes about all the rising cost of flying to some tropical destination for a fun filled vacation in the heat.

Enough already.

Time for a reality check.

Why do you fly?

  1. Because its faster, WAY FASTER – It takes less than 6 hours to fly to Mexico instead of 6 days of hard driving.
  2. Because its safer, MUCH SAFER – Statistically speaking you are far more likely to die in a car accident on your way to the airport, than in the airplane.
  3. Because its more comfortable, WELL MAYBE NOT – I argue that 6 hours in a sardine can will probably do better for your butt and back, than 60 hours in a car.
  4. Because its cheaper, WHAT? HOW? – Return air fare to Cancun is as little as $500/person from where I live, I paid over $1100 in gas alone to drive my family half that distance, to California last year.

There seems to be something out of place here. I realize that air travel is now the preferred way to get places in a hurry. But how can it be the best way to travel in all areas? To the average person there is probably no question here, who cares. But since I have an inside track on the industry, the math really doesn’t add up. There is no way the public should be getting this level of service for so cheap.

Case in point:

While doing some tidy up in the parts area at work, I decided to look up the purchase price of a few things. This was my favorite item by far.

Retainers for a DHC-8 Q400

These little circles (AKA retainers) are machined from aluminum and painted with Zinc-Chromate primer. They are about the size of your thumb nail (1 inch diameter) and are installed as part of the landing gear doors. What do you think they are worth? Maybe 20 cents?

No, they are machined parts and not mass produce so that will drive the cost up a bit, perhaps $1.00 each?

Wait! This is aviation, and aviation is expensive so I’d say more like $5.00 a piece….right?

Wait for it. Wait for it. Actual cost paid for these authentic parts…….$993.75………………EACH! That’s $1987.5 in that little baggy there. Good grief you’d think they were made out of solid gold with that price tag.

So the natural question should be, What makes them so expensive?

Its not the fancy materials they are made out of. No that’s just regular aluminum, probably 6061 which is not all that special. Its not that they took some huge number of man hours to produce, a CNC lathe probably turns out hundreds of these in an hour. Its not that fancy coating of green paint, that stuff is sold cheap by the gallon. Where is all that money going? What does $993.75 really get you here?


The bulk of money paid out in aviation is going directly into the pockets of the insurance companies. Why? Because if this little aluminum circle is deemed to be the cause of the crash. Then the manufacturer is going to be on the hook for paying out a couple million dollars for each and every person that died in said crash. So the insurance company needs to make sure that it has enough cash waiting in its coffers. And that means getting the little guy to pay out big. They have found a way to take advantage of the heavy regulation which surrounds aviation and keeps it safe. Or maybe they are just gouging?

This problem becomes very apparent when you are ordering parts that come from a common source. There are plenty of things on airplanes that a built by general manufacturers. There’s no way around this. Order a regular AN style bolt with a 10/32 thread on it. Pennies a piece right. They sell them by the pound for crying out loud. Until you want that little slip of paper which makes it certified authentic and usable on aircraft. Now all of a sudden we bump the decimal point over a couple notches, and a 1 cent bolt becomes a 1 dollar bolt.

Its ridiculous!Aviation is having a very difficult time moving forward due to this over the top charging system, yet somehow we see progress.

At any rate, next time you fly off to enjoy the heat of vacation and the flight attendant offers you a glass of water, instead of a beer. Before you complain about it, just remember that you are traveling in one of the most highly engineered pieces of equipment man has produced. Its fast, safe, reasonably comfortable and extremely cheap compared to the other options you had for travel. You chose this flight because it was by far the best option, and you should be grateful that they offer water at all on this flight.

Aviation Maintenance

Setup for success? I think not.

This is what it looks like when the electric propeller heat is active on the ground with no propeller movement:


Burning rubber and 8 composite blades destroyed.

The electric heaters installed on most IFR rated aircraft propellers can crank out a ton of energy in order to keep up with the extreme cold found at altitude. The heat will melt off any accumulated ice and prevent further ice from forming. Ice on propellers is a bad thing for two reasons; it reduces the thrust efficiency of the propeller, and, it creates an imbalance that can cause propeller and engine damage. That same heat will do damage to the propeller if there isn’t sufficient cooling available.

Normal operations would have the propeller heat switch in the OFF positions at all times, except when you want the prop heat applied during icing conditions at altitude. Unfortunately that switch was left ON in this situation.

Now, there is also fail safe in the scenario to prevent this expensive repair from happening. Normally the prop heat will only operate when a pressure switch senses that you have oil pressure on the affiliated engine, hence a running engine, thus the prop is supposed to be moving and can provide some cooling to itself via the air it is slicing through. So there are two switches that must be activated for the prop heat to operate, one is automatic and senses oil pressure, and the other is human controlled.

So what went wrong here? Although this aircraft is fairly new to the fleet, there are many more like it within the fleet, so this is not a problem with personnel being unfamiliar with aircraft systems.

Further investigation found that the pressure switch had failed at some time in its past history. In order to make the system operational again, the pressure switch was bypassed or hot wired. This means that the system will now apply heat to the propellers without the engines running. The safety has been bypassed, which means its up to personnel to ensure the switch is always OFF. Not really a bad thing as long as you remember to turn it off….right?

This is what I like to call “being setup for failure”. No one intended to fry the props. However a safety was bypassed to keep the operation rolling. Stress happens and the fragile human brain forgets to fix that hot-wire job when the aircraft returns from its flight. Time passes and the aircraft is sold. New operator has no immediate knowledge of the potential problem and all systems appear to work. All your waiting for now is the right combination of forgetful human nature and WHOOF, you have two cooked props.

So what are the lessons that can be learned from this expensive and sad situation:

  1. Always follow the pilots check list – the check list is there to make sure your brain doesn’t forget any steps, like turning off things that have potential to do damage.
  2. Always follow the full maintenance procedure – A full blown functional check of the prop heat should have found this fault before it caused damage, never trust the guy who did the job before you.
  3. Fix the problem the first time – Procrastinating only causes more problems in the long run, the pressure switch is small and cheap when compared to the propeller it is protecting.
  4. Prepare for the worst – Always check that the cockpit switches and circuit breakers are in the normal or power down positions BEFORE you apply ground power to the aircraft.

At the end of the day, everyone is responsible for their actions. If each of us endeavor to do the job right the first time, we greatly reduce the risk of failure. Every time we take a short cut, or skip steps, we increase the likely hood that something will go wrong. Then all it takes is time…and eventually it will go wrong.

Does this sound familiar – “We never seem to have time to fix it properly right now, but we always have plenty of time to fool around with it over and over again for the next 3 weeks.”

Lets remember to “Setup our colleagues for success…not failure”