M20J Carbon Monoxide, Need help !

[papagei]

Hello Mooniacs !

 

During the last year I've had a lot of trouble concerning the carbon monoxide readings in the cockpit. We used additional to the small carbon monoxide cards a digital carbon monoxide detector. But it only appears during the climb, being in cruise it is absolutely no problem an the readings will decrase quickly.

 

Now, we are at a loss. We checked and double checked everything, but we are unable to find a solution for this problem. Even our maintenance shop has no idea anymore.

 

We carried out the following work:

 

- We removed and checked the heat exchanger around the muffler. There have been no visible cracks, but for to be sure we also   removed during a test flight the heat ducting into the cabin. But it was without succes.

 

- We checked the complete exhaust system, from the cylinders to the tailpipe. Between the the muffler and the tailpipe was a leakage at the ball joint. There was a visible coverage of ash. We tightened the ball joint with a stronger spring kit and now it's absolutly leakproof. And again, it was ineffective.

 

- Because we don't have a one piece belly, we even taped the gaps at the belly with adhesive foil. We thought it is maybe possible that the carbon monoxide is entering the cabin by this way. Without any kind of result.

 

It's a '82 M20J, TTAF approximateley 2000hrs.

 

Do you have any idea, to explain or solve the phenomenon ? I think mooneyspace is the best platform to reach the absolutly best mooney experts. We are now at our wits' end.

 

Thanks a lot and best regards from Germany

 

Lukas

[Cruiser]

you don't say what the readings are? Does the button on the card turn black or only a high reading on your monitor?

Perhaps there is a problem with the monitor not working correctly?

[KSMooniac]

It could be entering through the door seal.

Sent from my ADR6425LVW using Tapatalk

[papagei]

I'm sorry, the readings are between 50 and 150 ppm. Usually one can say that per 1000ft AGL during the climb the readings will increase by 30 ppm. For example at 2500ft AGL 75ppm would be "normal". After a long climb also the button on the card turned black. Currently we are flying with two cards and the digital detector.

 

KSMooniac, thanks a lot ! We will check it! But as far as I can remember, the door seal seem to be new. Even in flight there is no coldness or draftcoming in.

[larryb]

No solutions, but a comparsision. I have the CO experts unit in my 84 J.  I see readings 20-30 on the ground, sometimes 10 or 15 in climb, and 0 in cruise.

[N601RX]

Remove the inside interior side panels and rear seat cushions. There are some gaps along the bottom that are 2" wide in spots. The factory sealed them with tape and caulk strip. The tape will eventually come loose.

[MARZ]

Also check the scat tubing going into the heat box - if there is anything coming off of the muffler you will be able to see grayish soot on the inside.  

[papagei]

N601RX, good idea ! I have also to mention that we have had one time mice in the aircraft, although it's hangared. Now we put some iron sheets around the wheels. Do you think it's possible that the mice came into the cabin over the main gear and destroyed the sealant or the tape you mentioned ? Will there be with a destroyed sealant a direct connection from the main gear into the cabin ? I think that could be an explanation.

 

@Mike Ropers: We already checked the scat tubing. So far it looked fine !

 

Thank you !

[N601RX]

If you have ever had a fuel leak on the tanks, especially around the inside sender unit the fuel will make the tape come loose. I found some 5" wide aluminum tape with fiber reinforcement from Mcmaster. I used 3m caulk strip on the small places I couldn't get tape. The bad part is cleaning all the old stuff . Also check the boots around the rudder pedals and main gear retract arms.

[papagei]

I've got some news !

Today, we did another test flight in our mooney. We decided to check the carbon monoxide situation with extended gear. So we climbed to 5000ft without any indication of carbon monoxide ( 0 ppm ), went in level flight, everything was fine. We decided to continue the climb, but now we retracted the gear and got immediately a carbon monoxide indication of ( 47 ppm ) after the short climb from 5000ft to 5500ft. So it was clear for us that this phenomenom only appears during the climb with retracted gear !

 

I also looked for the rat socks. They are in very poor condition. Im sure that this fabric isn't air-proof anymore. Do you think that would be a suitable explanation ? Here's a picture.

 

 

I also looked for some new rat socks, I found some on ebay:

 

http://www.ebay.com/itm/Mooney-Gear-Tube-Boots-/181298239291?pt=Motors_Aviation_Parts_Gear&hash=item2a3637973b&vxp=mtr

 

Do you think it's a realistic offer, or would you prefer another material or shop ?

 

Thanks and best regards

 

Lukas

[takair]

You may also want to check to nose wheel well and the nose gear doors. It's possible that the doors are not closing all the way and the airflow is such that it is getting in the cabin. You can see various pushrods in the wheel well that can leak.

[MARZ]

I bought the same in black.

Sent from my iPhone using Tapatalk

[Bob - S50]

No clue, but something to think about.  What is different between climb and cruise?  Cowl flaps for one.  Open for cooling during the climb, closed for cruise.  Maybe cooling air coming out the cowl flaps contains the CO, is directed toward a spot where it gets into the cabin.  Since we have a higher angle of attack at a slower speed for the climb, maybe the airflow is up and around the cowl and into the ram air intakes (or some other point).  With the gear down, the turbulence created by the gear may have changed the airflow and prevented the problem.

 

Just thinking.

 

Bob

[papagei]

We tried yesterday to install the new rat socks but have been unable to pull them over the gear pushrod. It wasn't possible to open the bolted connection you can see on the thin end of the rat socks. Do you have any ideas or instructions ? Thanks a lot !

 

 

Best regards

Lukas

[BillC]

Lukas,

I had the same problem with the socks that your having. So, I made my own socks. I cut the socks along the length and sewed in velcro to each side of the cut. Then I just wrapped the sock around the tube, attached the velcro to each other, and glued the leather base to the airframe. Works great.

Good Luck,

Bill

[jetdriven]

Check the rudder pedal boots and that 1.5" hole at the back of the nose gear well, on the rear of the gear well right above where the skin is. I taped that hole shut.

[papagei]

Thanks a lot for your suggestions ! Today we finally installed the rat socks. On the following test flight we still had round about 40 ppm carbon monoxide in the cockpit. So I looked as jetdriven mentioned closer to the rudder pedal boots. I removed the carpet and in fact there were several holes around them and it was possible to see the hangar ground. I hope that I can tell you tomorrow more after fixing them today with tape.

 

Best regards !

Lukas

[Seth]

Also check the boots around the rudder pedals and main gear retract arms.

My rudder pedal boots were torn and replacing them significantly reduced the exhaust smell when retracting the landing gear - exhaust was coming in the nose gear bay right into the cockpit on takeoff. That made a noticible difference.

-Seth

[carusoam]

The power of MooneySpace....

Best regards,

-a-

[papagei]

Just a short update. The work on the rudder pedal boots wasn't succesful. The monoxide still occurs. Due to the fact that it only appears during climb with retraced gear we will have a closer look on the cowl flaps area.

[N201MKTurbo]

To replace the rat socks you will need to put the plane on jacks, retract the wheels about 1/4 of the way and turn off the master and then pull the breaker. Now you can easily disconnect the linkage. Push the wheel to the down and locked position and slide the sock over the rod.

[DaV8or]

I have no real clue, but just brain storming... have you checked the alignment of your main gear doors? Maybe when the gear is all the way up, one of the main gear doors is hanging down a little bit and acting like an air scoop, forcing air and exhaust into the gear well? Maybe once the plane goes into cruise, the change in RPM, reduction in power, the leaner mixture and the closing of the cowl flaps shift the exhaust stream away from the gear door and the leaner mixture reduces the amount of CO?

 

Have you tried going into cruise and leaving the cowl flaps all the way open to see if the CO problem continues in that configuration?

 

Again, I have no clue.

[papagei]

We also tried to keep the cowl flaps open in level, but even then the monoxide decreases.

Today we checked the exhaust cavity panels, they have benn already sealed. During the following test flight the problem was still existent. I took some pictures of our work. Maybe an other M20J pilot is able to recognice any difference to his monoxide Free J.

 

I also attached a picture of the front gear. Do see there any abnormalities ? Do you think it's possible that the monoxide is entering here ? So far, we have no clue ....

 

 

Best regards

Lukas

[papagei]

And here is the floor without carpet and the sealed rudder pedal boots.

[ArtVandelay]

Have you tried moving you digital CO detector around:

At your side pedals, copilot side pedals, in front of each air vent, etc

I would think if it's accurate enough you should see a spike wherever the CO is coming in.