FlyingMonkey Posted September 20, 2013 Report Share Posted September 20, 2013 I have noticed that my OAT seems to always read at or very close to 89, even in obviously cooler air. The sensor is mounted on the underside of the airplane, and I started to suspect hot exhaust and cowl waste air were corrupting the readings. Today I did a test. In cruise the sensor was reading (shocker) 89 degrees. When I pulled power to idle, within 20-30 seconds the temperature reported by the sensor had decreased by five degrees at the same altitude. Theory confirmed! So I need to relocate the sensor, but how and where? My instructor's plane has it mounted through one of the plexiglass wing inspection panels, which seems a pretty good place. Is there a better place and can I do this easily, and is there an easy way to thread some kind of cap or plug into the old sensor hole to seal it off? Link to comment Share on other sites More sharing options...
Jim Meade Posted September 20, 2013 Report Share Posted September 20, 2013 Check with the manufacturer or try Van's Air Force forum. Generally, you want to avoid locations within the propwash or anywhere that will be affected by engine heat, including but not limited to exhaust. Mine is also located on the inspection plate under the left wing. Link to comment Share on other sites More sharing options...
Doug G. Posted September 20, 2013 Report Share Posted September 20, 2013 Definitely an LOA necessary modification. Link to comment Share on other sites More sharing options...
Jim Meade Posted September 20, 2013 Report Share Posted September 20, 2013 Definitely an LOA necessary modification. Mine came on the plane - maybe there is already an install authorization. Can ask FDUSA what they say. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 20, 2013 Report Share Posted September 20, 2013 The OAT on the bottom of the plane was installed after it came to the US. FD mounts them on the bottom of the left wing in the clear inspection port half way down the wing. I have changed 2 of these that some mechanic put on the bottom and they both read high and I have heard of others this way. It was a very poor choice, but I doubt they knew. The bottom gets the exhaust. There is a place that you can mount this within reach of the wires and it also has to be in the shade. It is up under (for shade) and by the flap on the fuselage. Just drill a hole and mount it in. You can buy a nice white plastic plug at Ace Aviation to put in the old hole. I doubt you'll need an LOA and it didn't have one to start. It's just a relocation, but you can call them and double check. If you need help give me a call. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 20, 2013 Author Report Share Posted September 20, 2013 Call me a wimp, but I think I'd rather move it to the inspection plate, even if I have to run new/longer wires..."just drill a hole in your fuselage" makes me a little nervous! Is there an easy way to run the wires from the Dynon to the inspection plate? It does not seem like there is a convenient and out of sight way to run those wires considering you have to get from the mushroom up into the wing... BTW I will call FD before doing anything. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 20, 2013 Report Share Posted September 20, 2013 Hi Andy, You would have to get extensions and try and run the wire down through the wing. (It isn't that easy) That's a bigger challenge than you think. Putting a small hole where I mentioned is no big deal and won't hurt or cause any problems and it's a 100% easier than trying to run new wire down the wing. Going into and through the wing may be a bigger bite than you want to take. It can be done, but the other way works just as well and you'll never know the difference. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 20, 2013 Author Report Share Posted September 20, 2013 Thanks Roger, I'll probably call you about this to get the exact spot you are talking about. I figured running that wire through the wing would be a PITA, and I'm not even sure how to get it from the mushroom to the wing; I don't know if there is an easy run to the baggage bay under the floor or through the door sill to the baggage bay and then up from there. In any event you'd need a good fish tape or something similar to get it through. Link to comment Share on other sites More sharing options...
Jim Meade Posted September 20, 2013 Report Share Posted September 20, 2013 Andy, let me suggest again to go to VansAirForce and search on this topic. You'll find a number of discussions and nearly any issue on location selection you can think of has been raised. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 20, 2013 Author Report Share Posted September 20, 2013 Andy, let me suggest again to go to VansAirForce and search on this topic. You'll find a number of discussions and nearly any issue on location selection you can think of has been raised. Sure Jim, I'll go check it out...I was just looking for the CT-specific information first. Link to comment Share on other sites More sharing options...
sandpiper Posted September 21, 2013 Report Share Posted September 21, 2013 Call me a wimp, but I think I'd rather move it to the inspection plate, even if I have to run new/longer wires..."just drill a hole in your fuselage" makes me a little nervous! Is there an easy way to run the wires from the Dynon to the inspection plate? It does not seem like there is a convenient and out of sight way to run those wires considering you have to get from the mushroom up into the wing... BTW I will call FD before doing anything. No problem! If the new hole starts developing cracks, just stop drill them. Joking. Seriously, I moved mine like Roger said. No problems and now the OAT works properly . Link to comment Share on other sites More sharing options...
Roger Lee Posted September 22, 2013 Report Share Posted September 22, 2013 The carbon fiber isn't fiberglass and you can drill it without an issue. You can poke a ice pick through carbon fiber, but not fibergalss. Now you can really worry. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 22, 2013 Author Report Share Posted September 22, 2013 I looked at the routing, and the hole drill might be the best way. I don't think the OAT wire has a lot of slack though, and I'm not sure where to run the wire, and exactly where to drill the hole. Still have to call FD and get the okay also. Link to comment Share on other sites More sharing options...
Jim Meade Posted September 22, 2013 Report Share Posted September 22, 2013 Where do the position light wires run? Is that route available? Link to comment Share on other sites More sharing options...
Roger Lee Posted September 22, 2013 Report Share Posted September 22, 2013 Hi Andy, All the ones I have re-routed had plenty of wire. Bring it up through the baggage compartment then up along side the opening behind the rear of the seat and on up to your drill spot. I don't have a picture of this location. If anyone does have a picture of this please post it for Andy. It would be up under the flap on the fuselage. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 22, 2013 Author Report Share Posted September 22, 2013 Where do the position light wires run? Is that route available? I think the problem with wing mounting is getting into the wing. From what I can tell, there is a bundle of wires going into each wing, but is inside a sleeve and then epoxy/painted over. One could maybe drill a hole alongside this, but they'd be drilling blind with no guarantee not to hit something important on the other side. The best way to relocate into the wing would be if the wings were removed. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 22, 2013 Report Share Posted September 22, 2013 Threading wire down the wing is not a walk in the park. It can be done and it came be done with the wing still on the plane, but pulled out about 15". It is a pain. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted September 25, 2013 Author Report Share Posted September 25, 2013 Flight Design USA said they think FD Germany will require a MRA (Major Repair or Alteration) authorization to move the OAT to the fuselage in the wing armpit spot, since it's a non-standard location. That being the case, I think I will just wait until the next time the wings have to come off and relocate the OAT sensor to the wing inspection panel at that time. Or if I get bored one day I'll see if I can thread something through the wing to where I can get to it in the fuselage. Not a big deal since it's just for true airspeed and wind indications on the Dynon, which are more just for additional info or curiosity than a requirement for safe operation. Link to comment Share on other sites More sharing options...
Roger Lee Posted September 25, 2013 Report Share Posted September 25, 2013 Then I would ask FD why all the dealers never sent in a alteration form when all the OAT's were mounted in various locations on the bottom of the plane. I have seen more than a dozen in just my shop so I don't have any idea how many are really out there. That would mean a lot of CT's would have to send in forms now. That may keep them busy for a while since they were mounted all over the place. Dynon just says out of the way from heat producing items i.e. exhaust and in the shade not in the sun. Link to comment Share on other sites More sharing options...
Jim Meade Posted September 25, 2013 Report Share Posted September 25, 2013 Then I would ask FD why all the dealers never sent in a alteration form when all the OAT's were mounted in various locations on the bottom of the plane. I have seen more than a dozen in just my shop so I don't have any idea how many are really out there. That would mean a lot of CT's would have to send in forms now. That may keep them busy for a while since they were mounted all over the place. Dynon just says out of the way from heat producing items i.e. exhaust and in the shade not in the sun. And not in the propwash Link to comment Share on other sites More sharing options...
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