Santa Fe: Engine Trouble

The flight to Santa Fe was relatively uneventful. We dodged a few thunderstorms, but it thinned out as we got closer. The controller wouldn't let us go VFR until we had the airfield in sight, and this proved to be more challenging than expected. There's something about the terrain that makes it hard to see until you're almost on top of it. We wound up visiting the tower and talking with the controllers and one fellow said he had the same problem even though he'd been flying the area for years.

We did eventually find the field, and touched down uneventfully. It was shortly after touchdown that we discovered we had a problem. The right engine on the Navajo stopped dead. At first, Steve thought it was just because he had kept it too rich and pulled the rpm back too much for the high altitude field. A CFI friend has since commented that on powerful turbocharged aircraft he never lets the rpms fall below about 1000.

We had noticed during the flight that the tach was acting funny too. I thought maybe it was an electrical tach and that it was likely an electrical problem that had killed the engine.

After trying the hot start procedure several times, we were unable to get the engine started. It wouldn't even pop. Clearly, something bigger was at work here. Reluctantly, we called a tug to drag us in. The Navajo will not taxi on one engine--it just tries to turn on the asymmetrical thrust and goes in circles.

Do you see a coyote in this picture?

While sitting in the doorway of the plane, waiting for the tug, it was very quiet and peaceful. I suddenly realized we were not alone. A coyote was standing next to the runway sign looking us over. You could see it clear as a bell with the unaided eye, but as you can see from the photo, I need to get a camera with a bigger lens to take these kinds of pictures!

Here's the U2 spy plane grainy closeup view of Mr. Wile E. Coyote, or is that one of Fidel Castro's nuclear missiles?

With this technology we might really have seen what goes on at Area 51 without overflying their airspace. Not!

I definitely want a longer lens. Yes, I have lens envy!

With about a 7:1 optical zoom and a 4-5 megapixel camera we'd be able to count the hairs on his shaggy little body. Trouble is, I'll probably never see I coyote under these circumstances again.

It's a sad, sad situation, and it's gettin' more and more absurd...

At least that's what Elton John says. Our dead and lifeless beached whale of an airplane is being towed in. Its good to see that this happens to expensive airplanes. For awhile I thought it only happened to my exotic cars. The feeling of embarassment and shame is approximately the same, which I found strangely reassuring.

The tug brought us here, near the FBO.

We sat in here for about an hour and a half, in the forlorn hope that if the engine cooled down it might prove to just be a hot start issue. The people at the FBO were very friendly and helpful. Their mechanic had gone home, and would not return for 2 days--it was a weekend. However, they did have a CFI who was also a mechanic. They called and he agreed to come out and take a look at it.

Needless to say, it wasn't simply a hot start problem. It cranked and cranked and didn't fire at all. By this time it was getting dark and everyone was tired. We agreed to meet Larry, our CFI/mechanic the next morning to try some more things. The FBO was also going to try to call their full-time mechanic to see if he would come in.

BTW, for non-pilots, the golf cart with the chequered flags comes out to guide you in from the runway. Since we had a tug, this service was not needed for the Navajo. Ahem.

The next day we showed up bright and early to meet Larry at 8 am. They fooled around with it while I strolled around the airfield checking out the various other planes. There was quite a lot to see, and I've included pix later on of the good ones.

Unfortunatley, Larry and Steve were unsuccessful in their efforts. At this point, Larry indicated he was in over his head and we needed a real full-time mechanic. Since Executive Aviation's mechanic was out and we didn't feel like waiting, we called the competing FBO, Jet Center, and they informed us their mechanic was in and could look at the Navajo as soon as he finished buttoning up a Cessna 206 he just finished working on.

Here it sits, waiting to be worked on...

It turned out to be about a 2 hour wait before he could start to look at the plane.

During all this waiting, Steve had occasion to call everyone he knew who had any possibility of knowing anything at all about a Navajo engine. You have to remember, Steve is a telephone guy. If he is near one, he has to be talking on it unless something really critical is going on. Short of an alligator gnawing on one leg, there isn't much that qualifies as critical either!

The consensus among these sages of the Navajo was that there was a problem with the "shower of sparks". I fancy myself knowing a thing or two about internal combustion, but I had never even heard of such a thing. It all sounded very fishy. Imagine my surprise when Zeke, our new mechanic announced that investigating the shower of sparks would be his first order of business.

I never did get a clear explanation of what a "shower of sparks" is, so I feel it is incumbant on me to explain here after having researched the issue. Basically, it is one of two methods by which the timing of the ignition spark is retarded at starting. Normal spark timing is relatively advanced so that it is optimal for an engine running at 1000 rpm or more. Because the pistons are moving rapidly relative to flame propogation from the spark, this works well. However, the speed is very slow at starting, and the spark occurs at the wrong point. In fact, if you try to start this way, it can result in kickbacks where the firing is so early that the engine tries to run backwards.

There are two fixes. First is to use an impulse coupling to change timing. Second, is to use a sort of external spark generating system that is separate from the magneto. It's called a "shower of sparks". It's basically a vibrator, like a doorbell buzzer, that just throws off a continuous high speed stream of sparks.

A little knowledge is a dangerous thing, eh?

To make it more interesting, and because we'd really weakened the battery with excessive cranking, Zeke trundled in an APU (Auxilliary Power Unit) and plugged that in. The APU is basically a good-sized diesel-generator on wheels. It has a honking big cable and is the prefered way to jump start everything from a Cessna 172 to a Boeing 747. It looks very cool and makes a helluva racket chugging away. There's also a faint smell of ozone to add to the overall effect.

Unfortunately, it looked like Mr Shower O' Sparks was healthy. This left just the magneto itself as our likely problem.

Zeke is inspecting the shower of sparks. Its installed in the nose because it is shared between the two engines.

The mighty APU is connected!

After considerable testing for bad timing, bad connections, and so forth, Zeke proclaimed that the magneto looked bad and needed to be pulled.

Steve has just gotten word that there is a magneto problem...

Looking at the ugly little spud I remarked that it sure didn't look like it had been recently overhauled, even though Steve had the plane in the shop for just that purpose before our departure. Zeke concurred, and as he got it out he mentioned that the overhaul sticker was not on the unit, and that it didn't appear to have many new parts. When pressed, he indicated it had no new parts. Hmmm, that's interesting. What did those overhaul guys do, anyway?

Steve got on the phone to see what the records said. Turns out they had only "repaired" the unit. Checking back, he noticed that the same mag had undergone "repairs" four times in the last 12 months! Why didn't the shop bozos tell him he needed a new one? I'd have been pissed if I was Steve. In fact, I would've been pissed after repair number 2 failed. Steve is more easygoing than I am, however.

Here is the bad magneto...

It isn't hard even for a layman to see that this mag has been rode hard and put up wet. For what those bozos (gee, don't read their name off the sticker!) charged Steve on the four prior repairs, he could've had a brand new one installed from the get go. From my perspective, they should have recommended that instead of just taking his money and potentially leaving him at risk of a bad magneto.

Oh well, live and learn.

 

 

Zeke actually traced the problem to a set of points that go to the shower of sparks. For some reason, they had loosened and closed in the shorted position, preventing any spark from being generated. He allowed as how he could simply reset the gap and get us going again, but that Steve really ought to think about getting another magneto soon. We nodded sagely and waited while Zeke got that mag back in and then taxiid out to the runup area to test his work. Things seemed to be going reasonably well for awhile and then he throttled back, the engine died again, and he couldn't get it started, so it had to be towed back to the hangar.

It's dead, Jim. Notice the odd angle? Even Zeke can't taxi on one engine!

This is not the sort of thing that inspires confidence. Zeke assured us he could make it work well enough to get us home, but that the mag needed to be replaced soon. Steve thought about it and decided to quit screwing around and just get Zeke to replace the mag. Hooray! Bob feels much better knowing we won't have to use grandpa's mag that had been in continuous service since WWII to fly home over the mountains!

Having made the decision to wait for a new magneto, stress levels were reduced, the schedule became less fluid, and we decided to take advantage of the situation in order to see Santa Fe.

I'll finish this lengthy tale before going on to describe what we saw in Santa Fe...

 

1 Echo Fox, dragged out of her warm lair with a new mag...

The mag was overnighted (actually it was door to door the same day with pickup at the airport, and Zeke installed it the next morning. Here we are wheeling her out of the nice warm hangar to see how well the new mag works.

Airplanes ought to be feminine, they're certainly finicky and high maintenance enough, no?

Prop not moving...

Prop moving!

Those two pictures tell it all. We like it when the prop moves. We love it when a plan comes together. After some more obligatory run-ups things seemed much happier. There was less mag drop and the engine started easier. We loaded the baggage while the mechanics put the engine covers back on and then managed to roar off into the sunset by about noon. Steve was muttering after take off that he wondered if there was any way to justify flying the plane back to Zeke for maintenance since the guys in the Bay Area were obviously inferior mechanics.

Thanks for all the help Zeke!

But don't miss out on what we saw in Santa Fe itself...

 
All material 2001-2006, Robert W. Warfield.