Aero archeology

I just got the bad news from the doctor. My engine has a year to live.

Oh. Wait. Don’t cry. Aircraft engines are more like cats. They have a strange immortality of sorts that grants them second, third, and sometimes fourth lives. You see, unlike dogs and humans, engines can be rebuilt. Made as new. Given a fresh life.

My engine is a Continental C-85-F. According to the company that gave birth to her, her life span is 1,800 hours. At that point they wash their hands of any responsibility and say the engine should be rebuilt. This is a big deal. The engine is dissembled. All the inside parts are cleaned, rebuilt, or replaced. The cylinders and pistons are thrown in a large trashcan and replaced with new ones. The spark-creating magnetos follow suit. In the end, for all practical purposes, you have a brand new engine.

For 1,800 hours. Then you have to do it again.

Still, we typically fly between 75 and 100 hours a year, which is much more than the fleet in general. A rebuilt engine will last me two decades. And now that I think about it, I’m not sure that I will last two more decades. So I guess the good news is that so long as I keep the Plane Tales Plane (and don’t buy a second plane) I’ll never have to live through another rebuild as long as I live. So that’s the black cloud’s silver lining.

The black cloud itself is $15,000 and two months of downtime. I’m not sure which is worse.

Complicating things somewhat are the missing logbooks. Planes have both engine and airframe logs, but given Tessie’s advanced age (69 this year) some of the logs, thus some of her history, is missing and therefore a mystery. One of those mysteries is the exact number of hours on the engine as mechanics past replaced hour-counting tachometers without noting the numbers logged on the replacement tachs. Were they zeroed? Were they used with counts of other engines? Were they reset to match units they replaced? No one knows and the logs are mute. This means that maybe our engine will live two more years, not one.

Another mystery is: When did the current engine join the airplane? She should have rolled out of the factory with a 75-horse engine, but now she has an 85. Where did it come from? A cryptic entry in a logbook from 1964 provides a tantalizing clue even while deepening the mystery.


Inside the front cover, with no date, is the following entry: This engine installed in Ercoupe 3976H.

It goes on to say that the engine was rebuilt at 1,858 hours. The serial numbers match the engine in the Plane Tales Plane. But there are two ways to read those five words. Are they telling us the engine was already installed in the plane and was rebuilt, or that they installed a freshly rebuilt engine into the plane? Was the entry made at the start of the logbook, or at the end? The first actual entries (with no dates) show an engine time of 294 hours. The log ends in 1991 with an entry at 1,710 hours. To me that suggests that the engine was, in fact, overhauled in 1964, and probably again before we got her. My Continental is on her third life, getting ready for her fourth.

Tessie’s third owner sent me some copies of old documents he had from the 50s. His pilot’s log shows that he was flying two Ercoupes at the time and he carefully noted that the other one had a 75-horse engine, but that Tess had an 85. This gives us circumstantial evidence that Tessie had an 85, possibly her current one, as far back as 1953. Giving us more clues, back in those days pilots logged flight hours via tachometer time, so while it’s not an official engine log, we “know” that her 85 horse engine had 193 hours on it in January of 1953. Adding to the evidence for the origin of her 85 being the 1950s, we also just learned that Tessie’s prop, based on its serial number, was one of the very early McCauley aluminum propellers, and most likely dates from the early 1950s. A separate mystery is when her wings were coated with metal, photos of 3976H in the 1950s show her factory fabric-covered wings were still on at that time.

But back to the engine, if the 85-horse engine joined the plane sometime in the early 1950s, it begs the question: What happened to her original engine? I can’t see why someone would replace a perfectly good engine with one only 10 horsepower larger, and yet it would appear that sometime in the first 3-5 years of her life, someone did.

I think this is one of those mysteries we’ll never know the answer to. Oh well. Every girl needs her secrets. Even ones with only a year to live.

5 thoughts on “Aero archeology

  1. Good possibility your C-85 came with N3976H. If you have not ordered a copy of the aircraft records from the FAA do so. The CD will have copies of old 337s. N3989H was born with the C-85. Now she has the STC for O-200 cylinders and crank. Still planning on flying to Vaughn this spring have business to take of there. I need to check some fence lines. Keep up the great work! I look forward to Friday morning. The first I do is read your column, what a great way to start a day!

    • Thanks so much for your kind words, Arlan. Let us know when you’ll be out to Vaughn and we’ll pop over and meet you for breakfast at Penny’s Diner.

      No, I haven’t ordered the records from the FAA. Actually, I didn’t know you could…. How does one go about that?

      • Never mind! So simple! I just entered “FAA airplane records” in a search engine and the right FAA page pops up. Ten clams per CD. Super simple. Off to get the records now… I’ll let you know what I learn!

        • Great, would like to meet you. I would post a couple pictures of N3989H but haven’t figured out how. There is one on landing Coolidge AZ flying.

          Is there fuel at Santa Rosa?

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