Boost pump connection

[Mooney-Shiner]

Happy weekend, everyone.

I had to send my electrical boost pump (Dukes 1499-00-19) to Aeromotors for the rebuild.  While I reinstalling the rebuilt pump on the plane the same way it was previously installed, I realized how flimsy the installation of the ground wire was to the body of the airplane. I tried to reference the Parts Catalog and Service Manual to see where and how exactly the ground wire should be attached and what nut and washer should be used.  But to my surprise there was no detailed the schematic on how the ground wire should be mounted, despite the fact that I view this part as a major airworthiness item. So I did my best to secure the ground wire to the floorboard best of my ability (as seen in the photos).  

Did anyone else ran into the same issue previously?

[RLCarter]

Not sure if it’s standard practice to have a ground and a clamp on the same stud (bolt) but I would think the clamp should go on first followed by the ground ring terminal then a star washer and nut.

[cferr59]

Here is a photo of mine.  It is somewhat hard to see, but it looks like there is a similar approach.  I thought it a bit strange when I reinstalled it, but it has been working since.

[Eight8Victor]

Here is another hard to see photo but might be of some help.

Edited July 11, 2021 by Eight8Victor

[Mooney-Shiner]

7 hours ago, RLCarter said:

Not sure if it’s standard practice to have a ground and a clamp on the same stud (bolt) but I would think the clamp should go on first followed by the ground ring terminal then a star washer and nut.

Yep, thats why I hoped that there was some manual reference to proper install. My rationale by attaching the negative eye terminal of the pump under the clamp to attach it as close to the main body as possible to provide a solid ground.  Additionally, if it is under the clamp and two nuts - this provided less likely possibility for the terminal to wobble out of attachment leaving me without the boost pump mid-flight.  But yeah, I wish there was a better dedicated attachment location.

[Mooney-Shiner]

6 hours ago, cferr59 said:

Here is a photo of mine.  It is somewhat hard to see, but it looks like there is a similar approach.  I thought it a bit strange when I reinstalled it, but it has been working since.

I can see that you attachment has AN365 self-locking nut, which make better sense to me than my own set up. I don't like the fact that my nut is not self-locking, which is not helping with accidental detachment due to the frame vibration. Or maybe I'm just overthinking this...

[kortopates]

7 minutes ago, ukrsindicat@yahoo.com said:

I can see that you attachment has AN365 self-locking nut, which make better sense to me than my own set up. I don't like the fact that my nut is not self-locking, which is not helping with accidental detachment due to the frame vibration. Or maybe I'm just overthinking this...

Did you consult your IPC for proper hardware? That specifies what to use.

Edited July 11, 2021 by kortopates

[Mooney-Shiner]

Just now, kortopates said:

Did you consult your IPC for proper hardware? That specifies what to use.

Kortopates,

Unlike the detailed IPCs of Encore, the Beatles-era IPCs of As-Fs provide rather marginal info of some areas of aircraft. As mentioned above, the rigging of boost pump is one of those areas.

 

[kortopates]

17 minutes ago, ukrsindicat@yahoo.com said:

Kortopates,

Unlike the detailed IPCs of Encore, the Beatles-era IPCs of As-Fs provide rather marginal info of some areas of aircraft. As mentioned above, the rigging of boost pump is one of those areas.

 

In that case, AC 43.13-1b Chapter 11 provides the guidance in the absence of manufacturer specific guidance. 

I am sure your fine with that, but woud measure resistance between your point for the boost pump ground and at another known good ground at the firewall or battery just to be sure it tests good.

[Mooney-Shiner]

1 hour ago, kortopates said:

In that case, AC 43.13-1b Chapter 11 provides the guidance in the absence of manufacturer specific guidance. 

I am sure your fine with that, but woud measure resistance between your point for the boost pump ground and at another known good ground at the firewall or battery just to be sure it tests good.

Thank you! I will look up AC 43.13-1b. Any suggestions on the good ground on plane's underbelly?

[carusoam]

Some really good input so far…

I invite @M20Doc for such tech discussions…

Don’t be afraid to use new hardware… when it comes to locking nuts, they sometimes give up their holding strength when re-used…

Best regards,

-a-