Long-EZ N31AK

POH, Trouble Shooting

This (work-in-progress) section will shown collected wisdom on N31AK. This will most frequently be accessed like a help section from the System and Detailed Procedure sections of the POH.


Amazing, you say. What could go wrong with a compass? Well, it can 'stick' preferentially to certain directions and mislead you a lot. If you're on a straight course for most of a minute, you can use the CRS off the Loran, set your HI, and use the HI and yaw bar graph to control precision turns. The compass isn't helpful.


The Loran basically works but it has problems in certain areas, like over the ocean just east of Pt Reyes. It will signal a Lat/Long error there and in other places.

The unit seems slow to correct itself after moderate or sharper turns. You can't trust your heading or ground speed readings until you've flown straight for about a minute.


I once smelled exhaust during a flight back from Camarillo. I had drilled holes in the firewall for mounting an Electronic Ignition and hadn't filled the holes. The morning was cold so I wasn't letting in much air through the forward vent. Opening the vent more increases cabin pressure and the gasses can't enter.


creaking during taxiing. not unusual.

resonances during startup and taxi. not unusual.

If your headset touches the canopy, you'll be treated to a possibly distressing resonance.


check that ANR (on headset is turned on).

check that cell phone turned off.

check buzzer assembly near right shoulder.


the vacuum gauge typically reads a little low, about 4.3" vs a published nominal of 5.2". This value is dependent on RPM. The 4.3" was also observed in an Archer. The gyros in both planes work.


The Directional Gyro precesses very little. Apparent precession problems were traced to the compass (of all things).

Oil temp too cold

The oil temp needs to be 180 degrees to boil off any moisture in it but, early in my time with the plane, it didn't reach 180. I now believe this was due to a resistive connection in the sender wire.

Oil temp too hot

I've experienced this twice taking off on a warm day when the plane hasn't had time to cool down from the last flight. In both cases, the temp gauge was just beyond the green arc. The remedy was to climb at a shallower angle and level off when able. Then I throttled back some and waited until the temps came down. Then I resumed the climbing needed to go home. The cool down seemed to take 5-10 minutes.

mpg poor

You have to fly high (8000' DA) to lean the engine safely. You can and should lean it 'waaaay' back. At 8000 DA, you can easily come back to about 1/3 the way from cutoff to full rich. Then move it slowly towards idle cutoff and listen for a drop in rpm. Make it a little richer to get the engine to smooth out. Check the EGT and CHT for the next couple of minutes.

top speed low

If the engine is turning the RPM stated in the performance table, at the altitude also given there, then you're getting the airspeed shown the table. If you're disappointed, the reason is likely that you're comparing it to IAS (Indicated AirSpeed), or what someone else told you. It's surprisingly difficult to measure and publish a solid value; it's very easy to be unwittingly comparing apples and oranges.

oil leaks

Historically oil has leaked from rubber tubing near the bottom of the engine, and from the large crankcase nut. Air flowing through the engine compartment can move spilled oil around. So clean the engine, mentally noting where larger drops are seen. With the cowlings removed, run the engine for 5 minutes and hunt for wet spots.

blue marks atop cowling

Fuel leaking from breather tubes. You were doing steep Chandelles over Lake Berryessa again, weren't you!

engine hard to start

This could be due to bad plugs; check the maintenance table to see when the plugs are due to be checked again. The bottom plugs will load up with lead balls. You might check the plugs.

8/5/08: start it w/ mixture back to about 50%; it seems to like that a LOT better than full rich. You should just able to squeeze the start of your thumb under the throttle (it's almost fully closed).

If you flood it, start with the mixture at idle cutoff (all the way towards the tail). While cranking, move it over 2 seconds towards the middle position.

If the engine isn't starting and you suspect that you haven't given it enough primes, you can quickly move the throttle up the 2/3 point and back to its nearly closed point. This will squirt gas into the intake manifold and will often start the engine. I'll often give it one official prime if the engine hasn't been run in more than a day then I'll use this technique to add a prime 'on the fly'.

(old entry:) The engine has been hard to start mainly due to my unfamiliarity with new conditions. The most practice I get is cold-starting the engine in the morning. That takes a known number of primer shots (see the sections on procedures and detailed ...). The next most common situation is starting just after buying fuel. The engine needs no priming. The most unfamiliar situation is when the plane has been sitting "awhile" after a flight, like after a $100 hamburger or breakfast with the Napa APB's.

If you think you might have over-primed the engine, keep the mixture full rich and put the throttle at the half way point (yes, when it does start, you need to back off the throttle very quickly). While cranking, move the throttle towards idle over 5-20 seconds.

file: c12_troubles.html