Nose gear bolt

[laytonl]

See the attached image.  I can’t find the bolt (circled in yellow) in the parts manual.  Any idea what size it is?  
 

My mechanic was replacing the gear donuts and discovered this bolt was in backwards.  he thinks the existing bolt may be undersized because there is a little play in the bolt.

I’ve owned the airplane for 12 years and the gear hasn’t had any significant maintenance since the donuts were replaced when I purchased it.  

 

lee

[PT20J]

Lee,

It looks to be an AN4-21. Interesting thing is that your drawing from the service manual shows it installed with the bolt head aft and the M20J IPC shows it installed with the bolt head forward which would be the standard way of doing things. You could call Frank Crawford and point out the discrepancy and see which is correct, but I’m betting the IPC is right.

 

[laytonl]

Thanks.  I looked in section 27-20 but missed the bolt. It is interesting that the parts manual doesn’t match the service manual.  The wording in the service manual explicitly says in bold type to install the bolt with the head in the rear.  Lee

[N201MKTurbo]

If I recall, that bolt hits something if it is put in backwards. Make sure you swing the gear while watching it (have someone ready to pull the breaker) and move the rudder from lock to lock while the gear is down.

You should have the doors unhooked so you can watch it.

[EricJ]

The 

47 minutes ago, laytonl said:

Thanks.  I looked in section 27-20 but missed the bolt. It is interesting that the parts manual doesn’t match the service manual.  The wording in the service manual explicitly says in bold type to install the bolt with the head in the rear.  Lee

Yes, there's a note in the SMM at the bottom of the column below the figure you posted that explicitly says to install the bolt back-to-front.   There are a bunch of earlier SBs that show it the other way, but all of the ones I have pre-date the M20J SMM.

Also note that the torque on the steering pivot bolt (3 in the diagram you posted) has an SI that specifies a much lower torque than the SMM.   The SMM says 450-500 in-lbs, and SIM20-109 says 270-300 in-lbs.

Both of these things seem to have had a lot of airplanes flying around in both conditions, so my guess is neither is extremely critical, but good to be aware of both, anyway.

 

[PT20J]

I missed the caution note in the SMM, so that should supersede the IPC. I had a damaged nose gear leg replaced last year. I'll look to see which way it's installed. Regarding the pivot bolt torque: the entire weight of the nose gear rests on the bottom plate and it wears over time so torque values are somewhat hit or miss. With a new leg, SIM20-209 torque works fine. With my old leg (which was 30 years old and about 1500 hours) that torque was too tight and I had to back it off one hole on the castle nut. Best way to set it is to start with the SI torque and then if the steering is too tight, back it off until it feels right.

[PT20J]

Found a picture. Installation agrees with Service Manual.