Saturday, 15 December 2012

TEST FLIGHT



Airplanes, like anything else mechanical, require maintenance to keep them in proper flying condition. In reality they don't need a whole lot more than the average family car does but let's just say that if airplanes were maintained the same as the average car, there would be a lot more of them falling out of the sky; it's a lot easier and safer to guide a car to a stop with a dead engine than it is an airplane. One could safely say that if cars were kept up the same way as airplanes they would be a lot more reliable and somewhat safer.

An airplane is required by law to be inspected and overhauled by qualified personnel at specific intervals. If those maintenance schedules are not followed, the pilot/owner can get into a lot of trouble, not to mention losing life and/or limb.

The various airforces throughout the world practice maintenance with military precision. Scheduled maintenance is performed to the letter and when the job is completed, all personnel involved with the work that was done are required to sign off (endorse) on it. Of course the only way to completely accomplish that is to test it under flying conditions. That means everyone involved climbs onboard for a test-flight and evaluation. I might add that it also tends to curtail sabotage should one of the maintenance personnel have a bone to pick with one of the regular flight crew.

Stew was in the Air Force for the duration of WWII and a little beyond. Although he was stationed at several different fields during his career, the type of aircraft he worked on the most was either the twin engined Avro Anson or the Cessna Crane with a dusting of deHavilland Gypsy Moth's thrown in for variety (that's another story). Stew's field of expertise was that of an aircraft electrician which meant that if it generated, used, or conducted electricity, Stew was the one who would be called to fix it. He found himself stuffed into the tightest of places, either an engine nacelle, under the dash, or down the fuselage chasing down a short or an open circuit, or else attempting to connect the wires to the terminals of a component that some engineeer hid behind something major and thus couldn't be reached by anything larger than a gnat.

Stew once told JC about such an incident where a generator failed on a radial engine on one of the Ansons and one of the other electricians removed it for repairs. Stew performed the actual repairs to the generator and handed it back. The electrician who removed it was rather small in stature but he discovered that reinstalling it was next to impossible as it was stuffed way up inside the engine cowling and one could either fit his hand in the opening, or the generator but not both--how he even got it out of there would forever be a mystery. Somehow the electrician managed to get the generator maneuvered into place and even properly secured to the gearcase but he still had to connect the wires to the terminals. He slid the eyes of the wires where they belonged but then the lock washers and securing nuts had to be attached and that's where everything fell apart.

He tried his best but failed; his sergeant tried but failed. With the two of them about to give up, the sergeant summoned Stew to see if he could manage. Stew came out, took a look at that tiny crevice then, without comment, smeared a bit of good old spit onto his index finger then pressed the first washer into the fleshy part of his fingertip. The washer sort of stuck there and Stew gingerly slid his hand up around the bulk of the generator and managed to set the washer onto the terminal. He followed with the nut. It took a great deal of effort but he was able to not only attach all the wires but also thread the weatherproof harness over them and finish the job.

Trainer planes got a lot of (more often than not) hard hours added up in a very short time. Consequently there came several times in the service life of an airplane when major work was needed. All jobs were broken down into intervals based on a specified number of flight hours. Different components needed attention at different times but there came the time when everything needed to be rebuilt at the same time; the engines, electrical components, radios, instruments, air frame and skin all came apart. The different components each got shuttled off to the various shops where the specialists quickly overhauled them.

This particular Anson went through such an excercise. The airplane was completely dismantled and the components stripped down, examined, evaluated, overhauled, put back together and certified. All components were reinstalled on the airplance where they awaited the final endorsement, the actual test flight. The job was completed in true, proficient, orderly, military manner, and in good time at that. Nothing was allowed to slip past, even with a trainer, because training aircraft often endured more abuse than those in combat--listening to JC recount his own experiences of his flying lessons gave testament to that. The job completed, the flight crew, and the maintenance crew wedged themselves on board and the tests began.

The engines were started and warmed up. Everything OK. The charging and lighting systems were all functioning properly, so Stew could relax a bit. The engines showed proper oil pressure and the mixture and throttle controls were funcitioning properly--so far, so good. One by one, the systems were checked off; the airplane was allowed to taxi, during which more checks and rechecks were performed, showing everything well within limits. Finally they were given clearance to take off.

The Anson left the ground and headed for the clouds. Further checks were conducted, all showing business as usual. The airplane flew straight and level, the elevators, ailerons and vertical stabilizer all doing what they were supposed to. The trim controls were also functioning the way they should. In fact the airplane was flying so well, the pilot decided to perform a climb at full power.

He firewalled the throttles and eased back on the column, guiding the aircraft upwards at twenty-plus degrees. The occupants all had to find something to hang onto to keep themselves from sliding towards the tail and possibly causing a sudden unbalance of the plane. All they could see ahead of them was sky.

There was no warning that something could be wrong; it happened so suddenly. A loud thump and a crash on the port side, accompanied by a ball of flame from the engine nacelle and the aircraft lurched to port. Those who saw anything caught a glimpse as the port-side prop and crankshaft exited the crankcase trailing a shower of debris and oil. Fortunately the pilot was experienced and immediately shut off the fuel to that engine while simultanteously bringing the Anson back to level flight.

Most twin-engine aircraft are designed to fly on one engine. They won't be able to take off but they can fly straight and level, and land with little difficulty. The trim tabs are designed to help the pilot hold the plane in control without too much strain. In this case the Anson flew with few problems other than having more than twice the normal number of passengers jammed into the fuselage like so many sardines. Luckily this incident occured over the vast prairies of Southwestern Alberta so all they had to do was head back to base and land--hoping that the wind wasn't blowing at gale force (common to the region) making landing with one engine very tricky.

Luck would be with them this day because they made it down in one piece, except the airplane, of course. An initial check proved that the front crankcase half, the part that bears all the thrust from the propeller, had given way (probably due to a tiny flaw that managed to escape detection despite the rigorous testing when the engine was apart) and the spinning prop just took off with the crankshaft and many other pieces, leaving a couple of cyliners and the gearcase attached to the airframe. Of course there was a complete investigation, part of which required a scavanging crew to be sent out along the flight path to retrieve the propeller, the crankshaft and all the pieces that came out with them.

That venerable Anson was once again restored to flight status and trained many more crews who would be deployed to the European Theater to man the likes of Wellington, Halifax and Lancaster bombers, amongst other heavy aircraft. Stew would remain in the Air Force until his discharge in 1946. He would then farm for a few years then move on to various jobs, eventually ending up as the setup man/delivery truck driver for the dealership where JC worked.


2 comments:

  1. Oh. My. Word! Really scary story! and all of those guys standing there, crammed inside that plane?! They should have had Stew put the whole engine together. A little spit might have made the difference!

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    1. Stew said they were crouched in there. The airplane was technically overloaded with the crew who had recently ingested a feed of boiled cabbage and liver so if someone developed gas that could've been worse that the engine failure. He said that when the engine blew up in that fireball, the real fear was the plane catching fire, but the fire blew itself right out. He said it looked so strange after they landed. The airplane parked on the apron with a virtually hollow engine nacelle.

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