Airplane Doctorin'
Recent research suggests that the annual physical exam has done little to impact mortality rates despite costing billions annually. Some doctors no longer recommend them, though mine is not one of them. However, when it comes to annual inspections for aircraft -- particularly older aircraft -- I think their value is self evident. My experience in 2016 serves as a perfect example.
For the first time in twelve years of ownership, I was not an active participant in the drop-off process for the Warrior's inspection. Ray (disambiguation: "
Helicopter Ray") simply retrieved the Warrior from my hangar and went to work.
Beforehand, I submitted a short list of squawks. A cracked oil cooler flange (discovered during the trip to Knoxville), a bit of oil seeping from the forward portion of the crankcase that Ray was already monitoring, and a couple of difficult hot starts reminiscent of the behavior observed when the
coil in the left magneto went bad previously (a factor in the
infamous carburetor fire of 2012).
The Warrior's oil cooler hangs on the back of the engine behind cylinder #4, adding a significant, vibrating mass to the baffling on that quarter of the engine. Fatigue cracks on the baffling nearest the oil cooler have been a consistent problem over the years, but now the cooler itself was cracked. This imperfect engineering explains why so many other designs place the cooler directly on the firewall and simply duct cooling air to it. When Ray removed the oil cooler, he discovered that it was cracked in more places than either of us realized and deemed it not worth repairing. A new oil cooler was soon hung from the same precarious position on the back of the engine occupied by its predecessor.
I had correctly diagnosed that the left magneto had an issue, but my focus on the coil was misplaced. Rather, the mag timing had slipped to a point where the coil was not firing at the proper time and this was the cause of the starting issues. Frankly, it is amazing to me that the mag timing could be so far out of tolerance, yet the engine ran well and passed every pre-flight magneto check.
Failure
On April 19, I received this worrisome text from Ray:
"Good morning, Chris. Call me when you get a chance."
Uh-oh.
I don't know which troubled me more, the vagary of the message or the fact that the laconically blunt aircraft doctor had bothered to type a pleasantry like "good morning" into his phone.
Cylinder number three did very poorly during the compression test. When Ray investigated, he found that the exhaust valve was in rough shape, invoking the technical term "hammered" when describing it to me. Investigating further, he found two cracks in the cylinder. The fact that the Lycoming powerplant performed so admirably on our most recent cross country flight to Knoxville, TN is a tribute to its robust design.
To be fair, I have been watching this cylinder since 2008. It has returned some erratic compression numbers in the past and, a few years ago, the shop did some work on the exhaust valve seat to improve the seal. I suspect that poor cooling on that cylinder, which passed undetected until I installed an engine analyzer, to be the underlying cause. I will never know for certain.
Thus, after roughly 1300 hours in service, Warrior 481's powerplant needed a new cylinder. Ray installed a nickel cylinder from Penn Yan Aero, changed the oil to an 80 weight mineral oil, and instructed me on proper break-in procedures. I will need to run at 75% or higher power and fly at least 30 minutes each flight without power reductions. This means no touch-and-goes, no short hops, and, though he did not forbid it, droning around at reduced power on instrument approaches is probably inadvisable as well. He indicated that the cylinder head temperature on number three would run hotter than the other cylinders for a time, but likely drop once the cylinder was broken in.
Hippy Hippy Shakes
| Date | Aircraft | Route of Flight | Time (hrs) | Total (hrs) |
| 25 Apr 2016 | N21481 | SDC (Sodus, NY) - 5G0 (Le Roy, NY) - SDC | 2.0 | 1531.6 |
I was anxious about the first flight after the airplane equivalent to open heart surgery (after all, it was a valve replacement). Improper torque on a bolt could lead to the departure of a recently installed barrel and that would make for a really crummy day.
Darrell had dropped off his airplane with Ray that morning and needed a ride home to Le Roy. We fired up the Warrior with this dual mission in mind. Having Darrell along for the first flight increased my anxiety, but he understood the risks as well as I.
When the engine fired, the airplane vibrated significantly like a wet dog shaking water from its coat. The engine monitor showed temperatures coming up on the pre-existing cylinders, but number 3 remained cold. With oil pressure looking good, I fed in some throttle. Over 1000 rpm, the engine suddenly smoothed and the temperature on number three rose to match those of its mates.
Disconcerted by the initial roughness, I suggested we taxi to the runway and evaluate how the engine performed on run-up. Darrell agreed.
At the departure end of runway 10, I locked the brakes and brought the engine to 2000 rpm. It ran smoothly with cylinder head temperatures rising appropriately. I completed the pre-flight run-up and returned the engine to idle. It continued to run true.
Satisfied, I keyed the microphone to announce our departure. I could hear from the side-tone that something was wrong. There was no "pop" when I keyed the push-to-talk button. The audio panel and the GNS-430 both indicated that I was not transmitting. I reached over to the right side yoke in front of Darrell and tested the push-to-talk switch there.
Pop...pop... Clearly, there was a bad connection in the circuit leading to my push-to-talk switch.
I aborted the test flight and taxied back to Ray's hangar, where he quickly found and repaired the broken wire to the pilot-side push-to-talk switch. With that, Darrell and I were ready for a second attempt at a test flight that would, hopefully, culminate in his safe delivery at the Le Roy Airport.
The second time around, the engine idled smoothly on initial start. After a successful run-up, we launched from runway 10, quickly climbed to 3,000 feet, and circled the Williamson-Sodus Airport. While I managed the climb-out, Darrell monitored engine temperatures and oil pressure. Circling the airport at 75% power, the engine continued to run smoothly. Cylinder head temperatures for the old cylinders fell into their usual 345°F range and, consistent with expectations, number three ran hotter at 385°F.
After a few circuits of the field, we reached consensus that all was well and set course for Le Roy, taking comfort in the fact that Greater Rochester International lay close to the direct route if anything went wrong.
Of Cylinder Replacements and Farmer's Fields
On the ground at Le Roy, Darrell and I were met by Ray, our good friend and the
owner/operator of the airport (not to be confused with "Helicopter Ray"). He was mowing when we landed and, recognizing the Warrior, parked his John Deere next to us on the ramp. I do not know whether he heard it from Darrell or "Helicopter Ray", but Ray was already aware of the Warrior's cylinder transplant operation.
Always ready with a story pertinent to the situation, Ray regaled Darrell and I with a tale from his time running the Hylan School of Aeronautics. He dispatched a pair of younger pilots to Watertown, NY to retrieve a flight school aircraft that had undergone similar engine work after an outright engine failure in northern New York state. He advised them to circle the Watertown airport for a few minutes after take-off before going cross-country in the repaired aircraft. The pilot flying the mended Cherokee did not heed Ray's advice and found himself putting the airplane into a farmer's field on the outskirts of Watertown after suffering an engine failure minutes after departure. The farmer loaded the crippled Cherokee onto a cart and treated airplane and its pilot to a hero's parade through Watertown on the way back to the airport. The young pilot had made a textbook off-airport landing without damaging the airplane, property, or livestock. Of course, had he followed Ray's recommendation in the first place, he would have been able to put the airplane back down at the airport without the necessity of a parade.
Darrell and I assisted Ray in moving a damaged Cessna 172 that had taken its elderly pilot for a ride several months earlier. It had scraped along the side of the old T-hangar structure at Le Roy. The Skyhawk's joyride ended when its propeller sliced completely through the hangar wall (explaining the sheet of plywood on the side of the hangar) and totaled an innocent aircraft resting inside. The 172's left wingtip was shredded and the propeller was completely mangled; it was twisted, bent, and deeply notched in places. It was an unfortunate demise for an otherwise honest, late 1960s-era Cessna.
Physical Therapy
I launched from Le Roy with a goal of contributing another hour toward the break-in of cylinder three. I flew to Geneseo, circled the National Warplane Museum, and noted that their C-47 D-Day Veteran,
Whiskey 7, was parked outside on the grass.
With the engine humming strong and smooth at 75% power, the airplane and I flew around the region at 3,000 feet. Cool, silky smooth air pushed our indicated airspeed into the bottom of the yellow arc as we hopped from airport to airport, first flying west toward Perry-Warsaw Airport, then back over Geneseo, Canandaigua, and Finger Lakes Regional in Seneca Falls. With nighttime rapidly drawing a shroud across the landscape below, I finally returned the Warrior to Earth at Sodus.
With two hours down, there are several more required on a modified flying regimen before the airplane will be back to herself again, but the road to recovery appears to be progressing well.
