Auxiliary or Boost Pumps in 2024

[SteveG]

After a cold flight yesterday my C337A has come down with a runny nose (boost pump overflow drip). I can't add much to the previous posts on this topic but... Repair or replace options now seem to be: Dukes overhaul at $1350 + $600 core, McFarlane (CJ Aviation) at $975 + $50 core or Weldon at $925 + $100 core. As previously discussed the McFarlane & Weldon pumps do not have the A thru D models included on their applicability lists. I'm just wondering if anyone has actually installed one of the non-Dukes options with the blessing of an IA or if everyone has eventually opted for the Dukes overhaul. It just seems crazy to pay $425 additional for an "overhaul" that no doubt reuses the same motor, housing, head casting, etc. such that all one is actually receiving is a reseal than to buy all new just to satisfy some obscure paperwork when all of the part numbers are interchangeable. I'm leaning towards the Weldon pump but if anyone has any experience with that solution I'd be grateful for your hard earned experience report. Or any further thoughts on the matter from others.

Thanks, Steve G.

[Frank Benvin]

Originally Posted by SteveG

After a cold flight yesterday my C337A has come down with a runny nose (boost pump overflow drip). I can't add much to the previous posts on this topic but... Repair or replace options now seem to be: Dukes overhaul at $1350 + $600 core, McFarlane (CJ Aviation) at $975 + $50 core or Weldon at $925 + $100 core. As previously discussed the McFarlane & Weldon pumps do not have the A thru D models included on their applicability lists. I'm just wondering if anyone has actually installed one of the non-Dukes options with the blessing of an IA or if everyone has eventually opted for the Dukes overhaul. It just seems crazy to pay $425 additional for an "overhaul" that no doubt reuses the same motor, housing, head casting, etc. such that all one is actually receiving is a reseal than to buy all new just to satisfy some obscure paperwork when all of the part numbers are interchangeable. I'm leaning towards the Weldon pump but if anyone has any experience with that solution I'd be grateful for your hard earned experience report. Or any further thoughts on the matter from others.

Thanks, Steve G.

See my post above You need to replace with the dukes with dukes The other ones are certified for the newer model 337's not our older 337's The fuel pumps in the older models are in the wings the newer ones are located in a different place the engine compartment if i remember correctly My mechanic told me to replace with the certified ones for my 337b I am located in Canada

[YankeeClipper]

I'll ask my IA tomorrow how we resolved. I don't recall breakfast, so...

[Learjetter]

One could use the grace in AC 20-62 and use the new pump in place of the old one. Just confirm same form, fit, function and that it’s a PMA’d article.

It would take a mechanic to deem it a minor alteration (logbook entry) or an IA to write it up as a major alteration (Form 337), or even get a field approval from the FSDO, depending on how conservative the owner is and how worried the mechanic is.

Personally, if it was mine, I’d call it a minor and go fly.


-LJ

[SteveG]

Dear Mr. Benvin, Thanks for the reply. I do understand where you are coming from however I do think Canada's maintenance engineers, as I believe they're known, and the regulations they operate under, are more restrictive than most. While it is true that later models relocated the pumps from the wings to a position closer to the fuel strainers, in the nose gear wheel well for the front and in the upper engine compartment for the rear, the pumps used are all the same make, model & part number. And so it escapes me why units PMA'd & STC'd to replace that part number should be rejected as unacceptable just because the early aircraft were omitted from the manufacturer's eligibility list. I've spoken with an IA who, although somewhat reluctantly, said that he could approve the installation so long as it involved matching part numbers or their equivalent. But I do not wish to cause him any discomfort unnecessarily.

Dear Mr. Clipper, Thanks. My short term memory is also measured in minutes, not hours or days.

I've not committed to a purchase as yet and so I remain interested in anyone's experience with any of the aforementioned pumps. The one I just pulled out has a date of manufacture of 5/6/1977 and so I suppose the Dukes has served a useful life although even 48 years probably only amounts to maybe an hour or so of run time. Given their limited use the motors would likely last forever, it's the seals that perish over time. And I believe that the rotor vanes have undergone a redesign so that may be a small improvement as well.

[SteveG]

Dear LJ, Yes, it's the form, fit & function argument along with compatible part numbers that I believe makes this PMA by other than the OEM solution acceptable. Thanks.