There are people who restore planes. Old planes. Planes from World War One when my grandfather learned to fly. When Dexter was in his first year of college one of his suite mates disappeared after a semester because his father was killed in a small plane accident. It turned out that it was in Paso Robles, where I flew for my check rides. When I looked into it, I read that it was a faithful model of an antique plane. A plane so old that it had no throttle, only an on-off button for the engine. It was at idle or it was roaring along. And, much later, I learned that the part of the plane that failed was in a spot where it could not be inspected.
That’s a design flaw. I am sure the person who drew the airplane would have made a change if they had known that the plane was going to be around and flown for a hundred years. In fact, every plane designer draws a plane and then immediately draws the next plane. There is always some way that they are improving things.
The fellow at the next tie down in Santa Monica had a Grumman Tiger. He told me they were built as simple trainers for WW2 pilots. Essentially disposable planes banged together for the war effort. He showed me how there was no way to get to the connection between the rudder cable and the pedals without destroying parts of the sheetmetal around the footwell. I think they had to do that every ten years to inspect (and replace as necessary). I am sure that the designer of that plane would make a few changes if they were building it today.
Our plane has gotten better by little bits every year that we have had it. Along with a superbly better autopilot and removing the control stick from the left seat, we’ve just sort of nudged it along toward perfection. So, of course, has Diamond. They now sell a version of our plane called the DA42-VIII. The pieces come out of the same mold that our plane’s pieces came out of. The engines are a pretty simple update to our engines. There are apparently a whole bunch of little aerodynamic improvements that deliver a blistering five knot increase in airspeed. Not the sort of improvements I would double our investment for.
But I like nudging it along, and some of the things that need to be done are suggested by the manufacturer. One of them seemed rather critical and required two weeks in the shop. After a while Diamond determined that it was important to be able to inspect the control rod rollers.
To move the control surfaces on a plane I know of three systems: cables and pulleys, push rods, and hydraulics. The last one is used on much larger, more powerful planes. The cable and pulley systems are what we started out with and are still on a lot of planes. One of the scariest aviation blog entries I have ever read was about a stray piece of debris floating around the inside of a wing during a zero-G maneuver and it getting caught in the pulley and cable system. That jammed the aileron controls, effectively putting the pilot in a situation at a few thousand feel where he didn’t have control over one of the axis of movement of the plane. I think I would have climbed out of the plane. Later!
The pushrod system in the Diamond is, in theory, safer than the pulleys. I guess it is less likely to break? There are definitely fewer parts to fail. So I was happy when we bought our first plane and it had pushrods. Diamond flew the first DA42 in 2002. In 2014 they started making them with inspection ports so that you could peek inside the wings and see the little plastic rollers that guided the control rods on their way to the bell cranks that moved the controls. Why? Because on deep inspection of some of the original planes they were discovering cracked rollers which had the potential to jam the controls. See above for my nightmare scenario.
So a bunch of inspection ports will be cut in the skin of our wings making it possible to peek inside to check, and if necessary replace, all of the control rod rollers. While things are apart they will replace all of the rollers preemptively. And now part of the annual inspection will be to check the rollers to see if any are cracked. The chances of the nightmare scenario recede considerably. Excellent.
My mechanic sent a photo with the wings removed. Because as long as the plane was in the shop for that long it was worth replacing the original fuel hoses (rubber) with those specified in new planes (teflon). It is possible for the rubber hoses to start seeping fuel. Not a feature.
When the plane was being used in a flight school (most of its life) the renters had to record the Hobbs time. That’s an hourly timer which shows tenths of an hour and starts clicking once the RPMs are above a certain threshold. That way you don’t pay your $200 per hour rental fee for the time you are sitting on the taxiway waiting for your instrument clearance. I did not enjoy hearing the ticking of that timer, so we disconnected it years ago. (I use the system’s Time In Use hourly timer for all of my logging and maintenance. There are debates raging about whether this is proper and how vague the plane’s Handbook is versus the actual regulations.)
Once the Hobbs meter was removed there was a hole in the instrument panel. My mechanic suggested a USB port, which is really nice for passengers to have handy (charge your phone, power your laptop). That has gone in. There will be a little work left to get it pretty, but I might do some of that with a shop here in New England.
My list of little items for the shop visit was a dozen and a half long. Two pages. Some of them are already handled and only took fifteen minutes. Some of them are my own curiosity about something (“Why are the struts so messy?”) which takes the mechanic almost no time to answer (“Possibly leaking seal, we’ve cleaned them up and we’ll keep an eye on them.”).
In a couple weeks I will pick up a plane that is a little closer to perfect. I am aware that this also helps the plane retain its value in the market. Every little bit we nudge it along, it keeps pace with brand new planes that people are now paying over a million dollars for.