Saturday, March 21, 2020

Not So Slick

 A $1000 Breakfast

Date Aircraft Route of Flight Time (hrs) Total (hrs)
07 Mar 2020 N21481 SDC (Sodus, NY) - DSV (Dansville, NY) 1.9 2095.9

Two ships launched from the Williamson Sodus Airport carrying six people to Dansville for breakfast on our second official Activities Committee event of 2020. Brad had Melodie and new member Brian with him in the Cirrus. Members Derek and Dan flew with me, our first time flying together.

As is my habit, we took the scenic route, making for Canandaigua Lake, then following low terrain to approach Dansville from the southeast. We landed a few minutes ahead of Brad and taxied to parking. I pulled the mixture to quench the engine and, as it stuttered to a stop, a loud, rapid, ratcheting sound came from Warrior 481's engine compartment.

Click...click...click...

The three of us looked at each other in puzzlement. I was reminded of the sound made by pulling on a car's parking brake lever.

"Um...did one of you do something weird with your seat?" I asked without much hope.

"Nope," my passengers answered together.

Dammit.

As Brad taxied in from landing, I stood with my back to the freezing wind blowing unfettered across the airport from the general direction of Lake Ontario and turned the propeller through. It did not seem to be dragging on anything. I checked the ring gear for clearance with the cowling or stray engine baffling and found nothing interfering. There was no obvious problem with the engine.

Cold and hungry, we walked to the nearby truck stop diner for an excellent breakfast and great -- largely aviation related --  conversation.

Brad, Melodie, Brian, Derek, Dan, and me at Dansville after breakfast.

Back at the airport, I repeated my previous inspection, this time checking to ensure that the starter was not partially engaged. It wasn't.

I called Ray for advice and we reviewed familiar ground. Ring gear rubbing on anything? Starter engaged? No to all. Ray suggested starting the engine and running it up. I did not get as far as a run up.

Brad's Cirrus. Photo by Dan.

The Lycoming was hesitant to start, which was an early clue to the problem. When it finally did catch, we heard a loud sound of gears meshing and whirring at low rpm. Horrified, I pulled the mixture immediately and the engine coughed to a stop. In the meantime, Brad and his passengers departed for home.

While Dan and Derek stayed in the Warrior for warmth, I ventured back out into the wind and removed the cowling. "Check that the mags and other accessories are all firmly attached," Ray advised after I described the sound made by the engine. I did. They were.

The Calvary Arrives

Eventually, Brad returned to rescue Derek and Dan from their inauspicious first flight with me. Shortly thereafter, Ray and Denny arrived in Denny's Comanche. Ray removed and inspected the lower plugs. One of them was surprisingly oily, but the others looked about as expected. With the plugs removed and zero compression in the cylinders, the prop turned over easily and smoothly without any apparent issues.

"Why don't I hear the impulse coupling?" Ray asked as he swept the prop through the position where there would usually be an audible click. I suddenly remembered the difficulty in starting the engine.

"Mag problem?" I asked.

Ray removed the back of the left mag while I turned the prop through several full rotations. "It's not turning," he informed me. Once the mag was removed, the issue became obvious.

Gouges evident in the mag housing from where impulse coupling components jammed the mechanism. Photo by Ray.

The impulse coupling had fallen apart. Gouges in the magneto's case were evident where the rotating mechanism was jammed by loose impulse coupling components.

Just call me toothless. Warrior 481's left mag gear. Photo by Ray.

Another angle on the left mag gear. Photo by Ray.

Teeth on the mag gear that mesh with gears in the engine accessory case were visibly ground down, likely the source of the ratcheting sound we heard. The oil was likely full of metal. While I rotated the engine with the prop, Ray inspected the accessory case gears and indicated that they looked OK. I could only surmise that the metal of the mag gear was softer than the other gears by design to avoid an engine stoppage should a mag seize up like mine had.

"I have never seen a failure like this," commented my very experienced mechanic while shaking his head.

Stuck on a remote ramp without a replacement mag and limited tools, there was not much more to do than re-cowl the Warrior and break out the tie-down ropes. For what it's worth, I enjoyed my ride home in Denny's Comanche, truly a Cadillac of the sky.

SB2-19A

Back at Sodus, we reviewed the logbooks. Ray replaced the left mag in 2018. It only had about 300 hours on it. Considering that this is a piece of equipment with a 500 hour inspection cycle, this failure was both surprisingly catastrophic and grossly premature.

"Known issue," Ray informed me after speaking with Champion Aerospace, the manufacturer of my Slick mags. Champion had issued service bulletin SB2-19A on 14 October 2019, then revised it on 14 February 2020. (Happy Valentines' Day?) The serial number of my mag was among those affected. It reads:

"There have been limited reports in which impulse coupling rivets have loosened relative to the factory placement. A loose or broken rivet could potentially enter the gear train of the engine resulting in damage to the gear train or damage to engine accessories and could potentially cause catastrophic engine failure."

Yep. That sums it up. It is never a comforting thought to learn that about a time bomb in your aircraft's powerplant.

We were completely unaware of the bulletin and so learned about it the hard way. Fellow former Le Roy pilot Darrell indicated that he received official notice of the bulletin from Cessna about a week after my mag disintegrated.

Silver Lining

Four days before Warrior 481's last flight, I drove to Michigan for a funeral. I considered flying, but between anticipated IMC conditions with possible icing and a headwind so strong that the flight time would have been stretched to four hours (normally 2.5 hours), I decided to make the five and half hour trip by car instead. Considering that the mag failure would have happened no matter what, I feel fortunate that it occurred on the ground in Dansville, NY rather than over Ontario, Canada while in or above an overcast cloud layer.

Abortive Rescue Attempt

Two weeks later on March 20, while the rest of us were sequestered in our homes owing to the COVID-19 pandemic, Ray drove to Dansville with a new mag courtesy of Champion. His goal was to dump the oil, flush the metal from the engine, add oil, install the new mag, and after a hopefully successful run-up, declare the Warrior fit to fly home where a more in-depth inspection could occur.

Thanks to Jeff in Dansville, who pulled the Warrior into the large hangar on the field, Ray was able to work indoors and out of the rain and 40 knot wind gusts. He became quickly discouraged, however, when a more careful examination revealed more extensive damage to the gear train in the accessory case than he originally observed. He also detected a larger chunk of metal in the oil sump that he could not flush out - likely a missing piece from the impulse coupling. There are still two unreconciled impulse coupling components at large somewhere in the engine.

For the foreseeable future, Warrior 481 remains stricken in Dansville until we have a new plan.