I received a most interesting phonecall from the FAA Flight Standards District Office today. It seems that one of our aircraft, who shall remain nameless, but whose initials are N8520U was spotted doing low-approaches at the decomissioned El Toro Air Force base near KSNA. The word was that the aircraft was flying appx 5-10' off of the deck, and doing practice landings there.
This might seem like a good idea on paper. Long hulking runways, fairly open area, cool evening. But El Toro is NOT an airport environment, and as such, the rules governing it are strict. Specifically:
§91.119 Minimum safe altitudes: General.
Except when necessary for takeoff or landing, you are not allowed
to fly below the following altitudes.
(a) Anywhere. If your power fails you must be able to make an
emergency landing without causing undue hazard to persons or
property on the surface.
(b) Over congested areas. An altitude of 1,000 feet above the
highest obstacle within a horizontal radius of 2,000 feet of the aircraft.
(c) Over other than congested areas. An altitude of 500 feet
above the surface, unless you're over open water or a sparsely
populated area. In that case, just stay at least 500 feet away
from any person, vessel, vehicle, or structure.
Now I understand that if El Toro Air Force Base was still an airport, this would not be an unsafe operation -- at least not until the Colonel saw you and decided to have you shot down. Regardless, the FSDO would like pilots to know the following:
El Toro is not an airport environment, and as such, there is no protection offered to you against obstacles. While it seems like a nifty place to practice low approaches, KSBD or KCNO remain the better bets here.
The entire Orange County community is very noise-sensitive, and their lawyers have pointy teeth. Rest assured, an incident over El Toro would draw the community's anti-GA fangs quicker than anything.
There is an unconfirmed rumor that the area near El Toro may be classified as a congested area soon. To be honest, I'm surprised it is not already. This would necessitate a minimum of 1,000 AGL flying.
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At the end of the day, however, the neighbors in El Toro were simply pissed off at the 172 dive-bombing their houses at 8pm at night. The best way to preserve our aviation vocation is to play nicely with the neighborhoods over which we fly. This includes following the KAJO or other noise abatement procedures, and it definitely includes playing by the rules when they apply.
So, please, fly nicely.
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In some other news:
Cessna 25R is having her landing gear system worked on. Then her 100hr will be complete.
Cessna 20U is having her elevator reskinned, and her wing attach-bolts replaced. We didn't like the looks of them when we changed the windshield. Oh, and she's getting a new windshield.
Cessna 04H completed her 100hr.
Piper 85Y is done baffling the mechanics. Her left engine was running rough due to 2 scored pistons and a spun main bearing.
A what? who?
Bear with me here.
This is a Lycoming IO-360. Piper 85Y uses a slightly smaller version, the IO-320, but this was the best image I could find.
This is a 4-cylinder engine arranged in a "boxer" configuration (think Subaru or VW beetle). Our particular IO-320 is a fuel-injected, 320 cubic-inch engine (about 5.3L in metric), and produces 160 horsepower at an ungodly torque value. It is also rated to run for 2,000 hours between overhauls. In 85Y, that equates to 340,000 nautical miles, or 387,000 statute miles. Not bad.
Here is one standing on its prop flange (prop attaches at the bottom) so you can see that it's pretty simple on the outside, and even simpler on the inside. The yellow "box" in the center is the crankcase, and the 4 black "jugs" are the cylinders. Inside each cylinder, a piston reciprocates and turns a crankshaft.
You can see here the cylinders have been removed. The actual crankcase is about 12" wide. All of the action happens inside of those cylinders.
The crankcase is designed to be "split" into halves to ease assembly.
What you see in there is the crankshaft and two of the four "connecting rods". The connecting rods literally connect the pistons, which slide up and down inside the cylinders and turn the crankshaft. The crankshaft rotates under the power which is transmitted from the pistons, to the connecting rods, and the motor produces power.
For more detail on the 4-stroke combustion cycle, NASA has a good write-up here
This is a case half. You can see 3 U-shaped channels which the crankshaft turns on. In order to prevent the crankshaft from wearing down these channels, a wedge of strong metal is sandwiched between -- this piece of metal is called the Main Bearing.
A crankshaft.
Now these parts are generally forged from steel, and the force they are designed to tolerate is measurable in tons. As such, you'd think the bearing which separated the crankshaft from the case itself would be pretty impressive.
Well, it is, but you wouldn't know it from looking.
Just two of those are sandwiched between the crankshaft and crankcase.
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So what does all of this have to do with 85Y?
It was this little slip of metal which was starting to work loose and wear against our crankshaft. This caused a strange vibration on runup in the 1800rpm band or so. According to our engine gurus, in about 25-50 hours, our bearing would have looked like this:
Which, if ignored, may have made our connecting rod look like this
And which, if somehow still ignored, would have made our engine look like this
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You can imagine that, at the wrong time, that could put a twin pilot into an uncomfortable position.
Luckily, we have caught this very early, and we are having the engine completely torn down and overhaulled. I do not have an ETA at this time, but I will share more when I know it.
Until then, if an engine doesn't feel right in your airplane, and it cannot be explained by turbulence or bad power settings -- trust your instinct. Have someone look it over.
Blue Skies, safe landings!
- Mike
