RHS

A good walk around is a must. Look to see that the controls are fully free and move in the correct sense. Are all the fairings, inspection panels and cowling on and correctly secured? Are the seats correctly reinstalled? Does the exhaust system have excessive movement?

A good move is to use a torch to check inside the engine cowlings and the engine bay. Any tools left behind?

This writer once found a screwdriver on top of the cylinders several hours after a 100-hourly inspection. The previous pilots had not found it. The aircraft was a Warrior with cowls that are easy to open and allow inspection of the engine bay and cylinders.

You do not normally remove large panels to inspect an engine after it has done some 15 hours. I did on an Aztec twin to find the source of a small oil leak on an engine cowl. I found that the exhaust manifold had not been secured to the cylinders at the 100-hourly. No gasket, some studs absent, and no nuts to hold the manifold to the cylinders. There was a gap between the manifold and the cylinders. ‘’Not happy Jan’’ was not quite the expression I used.

I once did a ferry flight on a Cessna 150 that had just completed a 100-hourly. Ten hours later the new owner dropped the cowls to find that both exhaust stacks had holes in them. So much for a full and proper inspection.

Regardless if it is a 50 or 100-hourly service, the first thing to do is to check to ensure that the oil has in fact been replaced. One instructor I know started the engine of a Cessna to find no oil pressure. He killed the engine and found no oil had been put in at the 50-hourly.

Luckily, the engine did not become a boat anchor.

Controls are an interesting one. Whenever I collect an aircraft after any service work I always ask if the controls were touched during the service. I can write a book on the stories of controls not being connected the correct way or, worse, just not connected.

I am aware of the story of the two guys in an aircraft that got to the holding point before they found that the controls had not been connected.

And then there was the pilotengineer who reversed the ailerons in a homebuilt. That is where the two person dual control check helps prevent such events. Do check that the flaps and trim work correctly.

The paperwork is also important. The logbooks need to be written up after a 100-hourly. Should the logs go with the aircraft or not? It is said that they should not in case the aircraft crashes. But the logs need to get back to the owner if they are not to stay with the maintenance shop. And there is the new maintenance release. That has to be carried with the aircraft. It is worthwhile checking to see that the next due date is correct and that the 50-hourly oil change has a plus or minus of five hours to give a bit of leeway. Check to see what you are going to use as the recording device for the maintenance time build-up, the tacho, the VDO or the Hobbs. It is usually not stated.

Start up. Idle at the normal rpm for the type. Let the oil pressure and temp come into the green, ditto the CHT, then taxi and check that the brakes work okay. At the run-up the magneto check should be smooth and even. Check the vacuum pressure. Too low could indicate that the vac pump is on the way out. Check the idle, typically between 600 and 800 rpm. Too low or too high says back to the maintenance shop.

The first flight after maintenance should be treated as a test flight. Know the glide speed of the machine. Take time to double check all the gauges at the run-up before taking flight. In flight, do check that the gauges read in the green and normal. Stay close to the airport just in case.

Remember, that first flight after maintenance is the time to be wary of potential problems. Murphy’s Law says they can happen.

Instructor tip of the month

Doing a cross-country flight and overnight stop? Using a portable device such as an iPad, GPS or mobile phone? To ensure full charge next day the first priority at your destination should be to start the recharge. Double check that you have turned the power point switch on. To ensure that you do not leave the device behind next day put your flight bag next to it as a reminder.