Mechanic pet pieves

by | 2019-02-16

So what do mechanics think anyway ?

Flying your own aircraft is not the same as flying some else’s. When flying professionally, optimizing the operation to reduce down time is quite desirable. Operating within the aircraft limitations and the SOP’s provide the crew with good basic details in that respect. Some elect to go further within limitations to improve times, fuel consumption and wear. For many, appreciation for the flying machine extends far beyond the bread and butter notion of working. 

And when it comes to maintenance, most of the time, one is out of the loop once the snag has been written up. The cost of doing business, aside from fuel and insurance, is almost concentrated on maintenance issues. It is a well deserved tribute that must be paid to aircraft manufacturers when one understands what is being imposed on an airframe during a one hour training flight of touch and goes in the case of general aviation.

Airplanes are built tough

From the gut wrenching shock cooling on the engine to the vibrating sheet metal wobbling of a not so much continued flare, the aircraft absorbs with repetition. For good measure, toss in numerous steep turns followed by a few power on stalls (bring in those electronic gyros, please !) That is where serious engineering has been created. « Modern » airplanes are impressive. They are very forgiving when well maintained.

In the quiet land of owning, there is still a need to supervise our delicate operation if only to avoid suffering airborne failures. The less an aircraft is exposed to its operating limits the fewer chances the mechanical systems will fail. Further, one does not appreciate uselessly spending on frivolous maintenance if the operating style can be adjusted.

What can be done in that respect? Well, training whenever it was provided the last time, did cover basic knowledge. How to check the oil, having enough yet not too much, completing a good walk-around inspection and respecting the manufacturer’s limitations are the basics. Let the mechanics, handle the rest.

In come the mechanics

That makes sense in the perfect world. Flying can only be accomplished with the collaboration of many people. Mechanics are an important part of those collaborators and the ones we entrust our safety directly. It is only logic to call upon their experience to favourably improve flying efficiency. Going even as far as reducing maintenance cost. 

By the way, they are not worried of loosing business. Nature of the industry provides work all the time. I am always reminded when I have a chat with « my » mechanics over at Aviation R.Goulet on how they appreciate their work in problem solving and the appeasing satisfaction of knowing that the machine does not come back with the same snag over and over.

Engine manufacturers provide valuable literature to optimize engine life in the course of operations, they are worth your attention. In the field, mechanics have many pet peeves, pointers on how to avoid common snags that they observe for engine and airframe operations.

Maintenance cost savings, short or long term

I have attempted to list the prevalent ideas submitted. I have not paid attention to any scientific order nor do I pretend that the list is complete. There is no special scientific order in the following points. They are meant to supplement manufacturers and previously acquired knowledge.

  • Retractable landing gear being used as speed brakes.
    • When selecting the landing gear at or near its Vlo, to conveniently slow down the aircraft, will produce a lot of wear in the mechanical linkages. All those expensive stories one hears about worn bushings and bearings, trunions, etc… Come mostly from this. Sure, it’s a pain to wait for speed to bleed back on that sleek machine. That’s life. Simple planning and patience will help in this respect.
  • Extending flaps close to Vfe, does the same thing. 
    • Sure it’s allowed in the POH but in the long run the wear sets in. Changing flap track$ is an element of concern. Same applies to forgetting the high lift devices past their max speed is just as difficult on the metal. Engineering provides the numbers based on clean systems. Rust, grime and sand are not evaluated when they cover bearings, tracks, etc…
  • On the subject of retractable hardware: landing lights. 
    • The expensive little motors (on some models) that push out the beams need to be pampered. They are not meant to be cool speedbrakes.
  • Riding the brakes with power not at idle. 
    • A classic return business for brake jobs. No one would ever do this in an automobile…
  • Aircraft exhaust pipes are expensive to repair. 
    • The one thing that keeps them cracking is the dead mag check, also known as the P-lead verification. Should this check be done, ensure that the engine is at the absolute minimum idle in order to avoid detonation in the exhaust pipes. Avoid running the risk of having unburned gases being pushed out into a hot exhaust system. Older, eroded and consequently thinner walled exhaust, crack at that point.
    • Never do this test by switching the double mag switch (key type) to OFF. Instead select one magneto at a time to observe RPM drop, then going to both again. 
    • While we have a crack at this, turbo engines need to be absolutely pampered and operated with the tight limitations.
  • Under inflated tires are a nogo. 
    • Flat tires will always happen under such conditions. Tires will spin on their hubs making valve splitting a regular issue.
    • Flat tires at high speed cause control issues anytime.
    • Overinflated tires are a factor, they cannot absorb energy as well on landing. They do not allow for optimal braking due to reduce rubber exposure on the runway.
  • Installing pitot covers when parked outside. 
    • Especially in the Spring. Insects cause issues all the time within the dynamic instruments lines.
  • Believe it or not, a lot of us do not drain the fuel tanks all that much.
    • Should engine failures not be problematic instantly due to water ingestion, rust and grime accumulation in fuel strainers will cause problems. That is where eventual engine failures will also be a going concern. Never mind changing corroded parts.
  • Speaking of water in the tanks, fuel tank caps seals should be in pristine condition.
  • Headset cords wrapped around the control column. 
    • They are relatively inexpensive to replace but the heavy maintenance problem from a stuck control column are more of an issue here.
  • Headsets stored on top of the glareshield. 
    • They really scratch that windshied. On the short term, traffic spotting becomes a factor. Eyes focus on the immediate range of those scratches not on the far distance. Eventually long term neglect produces altogether a replacement requirement. Anyone out there appreciates a flimsy windshield?
  • Keeping the seat tracks clean and lubricated.
    • Should you find your seat being difficult to move fore and aft, there is an issue to solve. A seemingly locked seat not being secured is nothing more than a fatal scenario in the making. How many accidents happen on rotation when a seat promptly rolls back to its stop?
  • Floor corrosion.
    • This is a big one here. Specifically for the winter flyers. Try to have passengers shake off snow and all those salty accumulations from the boots.
  • Repetitive moisture exposure in the flight deck is not good for all sorts of corrosion within avionics, electrics et all.
  • Inadequate engine warming prior departure.
    • The hardship induced on the engine are unforgiving in the long run.
    • Not installing a winter kit in the winter induces the same kind of wear.
  • Slam, bang, push, pull throttle operations need to be emphasized.
    • Want to get to that TBO? Treat the engine most politely.
    • Constant speed props are even more prone to damage under improper management.
    • Always remember that a prop strike engine inspection shall be considered when a 200 RPM sudden drop occurred. 
  • The other side of difficult engine operation is lack thereof ie simply not flying an aircraft. 
    • A typical aircraft engine should be run for 30 minutes at cruise power every week. Simple engine starting and run up while not going flying does not clear the acids that accumulate within. Acids produce corrosion.
    • The notion that an airplane flown regularly will cost less, much less in maintenance comes in part from this requirement.
  • Keeping close look on batteries.
    • Modern batteries are great but many are still full of acid. Should this acid not be contained, it will flow through the breather and create all sorts of corrosion within it’s containment box and neighbouring structures (firewalls anyone?). Worse scenario is having streaks of corrosion along the aircraft belly caused by a leaking breather.
  • Keeping that aircraft belly clean.
    • Yup, it’s indeed a pain to fulfil. This will immensely help in locating problems prior they become expensive to rectify.

As this list can be improved we would be happy to hear from you should you have any pointers to contribute.

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