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.

6 comments:

  1. That really stinks! I didn't know about the SB, thanks for posting. I immediately checked my new mag and my older left mag model number 4372. Thankfully both of my mags did not fall in that range of serial numbers.

    I hope you get things fixed and back to flying very soon. Having the plane away from home, out of your control, is never a good feeling. At least she is in a hangar.

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    1. I figured that, minimally, I could raise some awareness among my pilot friends about the issue. You're the second person I know of who ran and checked the serial numbers on their mags after reading the post.

      I would be annoyed if she were stuck at home. My distress comes from being out of my control. The move inside was temporary. She's probably back out on the ramp. Even with cowl plugs, Ray still had to remove nesting material from the engine compartment last week. 'Tis the season, I guess, and you know how aggressive our feathered friends are this time of year.

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  2. Ugh, sucks. But as glad as you are that it occurred on the ground! And hey, at least it's during a period when the $100 Hamburger is temporarily out of commission.

    Personally there's some relief in knowing there's a SB out there on it; better than a completely unexplained failure. Hope that possibly helps with the ultimate cost and hassle of getting everything fixed.

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    1. Ray is hoping (with reason) that they'll cover the repair cost in addition to providing a new mag (which they've already done). He has a good relationship with the engine shop in Penn Yan (a big customer of Champion's, as you might imagine) and he's hoping to leverage that to our advantage. Even if we had seen the SB, we're still within the compliance window (inspection required within the next 100 hours).

      Current plan is to go back down (at some point) with all of the accessory gears, open up the accessory case, and replace anything that's damaged. It's not a small job - mags, oil pump, fuel pump, and vacuum pump all need to come off - but he thinks he can do it in a day. He also wants to inspect the oil pump because it is positioned before the oil filter and after the screen. So no big chunks would have gone through the oil pump, but the fines may have before being caught in the filter.

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    2. Yeah that's no small task. But not much you can do except inspect everything as fully as possible at this point. Sorry you're grounded indefinitely. Seems most things right now are on an indefinite timetable!

      Have you given any thought (not that additional $$$ outlay is highly desirable at this point) to adding another G5 and removing the vacuum system in the process, since it'll already be torn apart?

      I do hope we'll all be able to coordinate a meetup at LBE or elsewhere sometime later this year!

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    3. That was my plan this year. The avionics shops around here seem to be very backed up. The engine work and the avionics work won't happen in the same shop, so we'll see what happens. I have an annual and a transponder cert coming due next month, so hopefully we get the plane out of Dansville before it goes out of annual.

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