Nukemzzz Posted January 28, 2021 Author Report Posted January 28, 2021 9 hours ago, N201MKTurbo said: But it does seem to maintain a stable rate after it is adjusted. Maybe there was a method to their madness. For some reason the engineers used a large diameter adjustable flat orifice to control the retract flow. This is very sensitive dimensionally. The flow could have been controlled more precisely with a conical or needle valve up or downstream of the ball instead of trying to integrate it into the ball pre-load and capture system. They may have had their reasons, i just can't see it...perhaps because I haven't tested the designs that I have in mind to discover the issue they saw.
N201MKTurbo Posted January 28, 2021 Report Posted January 28, 2021 28 minutes ago, Nukemzzz said: For some reason the engineers used a large diameter adjustable flat orifice to control the retract flow. This is very sensitive dimensionally. The flow could have been controlled more precisely with a conical or needle valve up or downstream of the ball instead of trying to integrate it into the ball pre-load and capture system. They may have had their reasons, i just can't see it...perhaps because I haven't tested the designs that I have in mind to discover the issue they saw. What you propose would probably work better, but it would require a bigger, heavier pump with more parts and more machining operations. Maybe their goal was to save weight and money? After all we are talking about something that is done rarely, takes a minute or two longer to adjust than a more elegant solution and works perfect after adjustment. 3
LantisPDX Posted February 22, 2021 Report Posted February 22, 2021 Thanks for all the advice that was given. I ended up on an extended trip to San Diego in the plane so I have not had a chance to work on the flaps. I will be working with my mechanic to recoin the 3/16" ball when I return, as I agree, it really sounds like the problem spot. We had tried to recoin it at the time but I think we need to be a little more aggressive. I am excited to get home and to get the flaps working correctly!
M20F Posted March 26, 2021 Report Posted March 26, 2021 On 4/14/2020 at 12:15 AM, Nukemzzz said: By uniquely qualified I mean... I’ve been a mechanical engineer for diesel fuel injection systems for 18yrs. 6 of those years leading the development and launch of these systems into Europe. 2yrs Prior to the 18 I was a service engineer explaining to technicians around the world how to troubleshoot Diesel engines (creating diagrams and steps like attached...but more professionally done...not in PowerPoint). The 9 years before that I was a certified auto/diesel technician. My current job is an engineering reliability leader and manager for the same systems. The majority of this current job consists of engineers presentIng to me their troubleshooting of design failures trying to convince me that they know what went wrong and how to fix it (answer is often no...lol). I stayed at a Holiday Inn Express last night.
303mooney Posted January 15 Report Posted January 15 Does anyone know that the part I have circled is and what it does? Upon disassembling my flap pump for a rebuild, it was noticed that I am completely missing this piece. The flaps were functioning normally, just a small leak from in between the halves.
N201MKTurbo Posted January 15 Report Posted January 15 12 minutes ago, 303mooney said: Does anyone know that the part I have circled is and what it does? Upon disassembling my flap pump for a rebuild, it was noticed that I am completely missing this piece. The flaps were functioning normally, just a small leak from in between the halves. That piece is pushed by the shaft with the eccentric to unseat the 3/16 ball to let the flaps up. 1
303mooney Posted January 15 Report Posted January 15 18 minutes ago, N201MKTurbo said: That piece is pushed by the shaft with the eccentric to unseat the 3/16 ball to let the flaps up. I'm wondering how my flaps have been working all this time without it. Is it a part I can find and replace, or do I need to replace the entire pump?
N201MKTurbo Posted January 15 Report Posted January 15 5 minutes ago, 303mooney said: I'm wondering how my flaps have been working all this time without it. Is it a part I can find and replace, or do I need to replace the entire pump? Are you sure it isn’t still in the valve body? 2
303mooney Posted Tuesday at 02:40 AM Report Posted Tuesday at 02:40 AM On 1/14/2026 at 10:02 PM, N201MKTurbo said: Are you sure it isn’t still in the valve body? Positive. Took it all apart and it 100% was not in there. I also noticed that Allen head bolt was screwed all the way in, while on photos of others, it's backed out a bit.
N201MKTurbo Posted Tuesday at 03:10 AM Report Posted Tuesday at 03:10 AM 29 minutes ago, 303mooney said: Positive. Took it all apart and it 100% was not in there. I also noticed that Allen head bolt was screwed all the way in, while on photos of others, it's backed out a bit. The Allen head bolt is just a plug. It just gives access to remove the part you are missing. So can you see through the valve body from front to back?
303mooney Posted Tuesday at 09:24 AM Report Posted Tuesday at 09:24 AM 6 hours ago, N201MKTurbo said: The Allen head bolt is just a plug. It just gives access to remove the part you are missing. So can you see through the valve body from front to back? Yes. Nothing else in there except the eccentric rotating part, which when removed I can see the other side of the bleed speed ball. The part is not there.
N201MKTurbo Posted Tuesday at 01:38 PM Report Posted Tuesday at 01:38 PM 4 hours ago, 303mooney said: Yes. Nothing else in there except the eccentric rotating part, which when removed I can see the other side of the bleed speed ball. The part is not there. OK, its missing. You will have to find one or make one.
303mooney Posted yesterday at 06:12 AM Report Posted yesterday at 06:12 AM 16 hours ago, N201MKTurbo said: OK, its missing. You will have to find one or make one. So interesting update. I purchased a used flap pump, also from a 1967 M20F like mine, and it also does not have that part... was the part a revision, or am I just losing my mind
303mooney Posted yesterday at 06:31 AM Report Posted yesterday at 06:31 AM Also that Allen head bolt is flat on the inner side, instead of conical like the diagram. It is like that for both flap pumps in front of me
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