Shadrach
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Everything posted by Shadrach
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This thread is starting to take a turn for the silly. No one here is obligated to use an OPP. No one here is required to sign off on any OPP. There is lots of guidance on this issue. It’s a free country and no one is forcing anyone to participate in the process.
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There’s no disconnect at all. Sending my old boot to someone that I know to have expertise in the fabrication of custom rubber ducts is no different then sending a part to a machine shop for duplicatation.
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You've done an excellent job of articulating your position. You keep talking about a collapse that chokes the engine to failure. In the history of the fleet, there has been one incident of a hastily repaired duct that resulted in an engine failure. I have not seen the failed unit but given my experience with the duct, I would bet that the engine failure was very likely caused by whatever materials were used in the lousy repair being sucked into the torn intake and creating an immediate blockage and or pressure drop that may have collapsed the whole mess. The failure would have likely never happened had the duct been left alone...even if it was a torn mess. Have you ever replaced one? I am sure there are folks that are faster and more competent than me, but it's kind of a PITA to R&R. You either drop the cowl or finesse your way around the exhaust and intake tubes. 10 bolts in close quarters 4 of which need to be safety wired. Is it a big deal? no...would I rather not have to replace it every 5 years, you betcha. Aviation maintenance expenses come in many forms. The big ticket items...I have one engine overhaul, one engine IRAN, a case OH and 3 prop overhauls under my belt (just off the top of my head). And the smaller items...I have 3 generators, two starters, an oil cooler OH, a new prop governor. Several vacuum pumps, mag OHs, tank repairs, instrument OHs, exhaust OH, gear blocks, shock discs, tires, brakes, etc...etc. It's the "death of 1000 cuts" analogy. I have not tallied the outlay for "small" expenses over the last few decades, I don't really want to know, but I can say with certainty that it's enough to want to minimize a "cut" when I can.
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In my experience, these ducts are susceptible to both age and use. I am on my 4th in 22 years and 1600hrs. If that qualifies as robust, our standards are quite different. It could be that more short hops wear it out faster as I think startup and shutdown are hardest on the duct. By the time a failure is externally obvious, there’s a good chance it’s been sucking unfiltered air for a while. Do you decowl your plane and inspect before each flight? There are lots of things we did really well in the sixty’s, wood fabrication, metallurgy and machining to name a few. However, in the case of precision made, lightweight, flexible ducting, design and materials have come a long way.
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I’ll speak for myself only. I supported making an OPP part to the exact dimensions of the OEM duct out of equal or better material. When it was mentioned that McFarlane is seeking PMAs to add to their portfolio, I suggested that improved design and materials would be welcomed. Aeromotors has made a number of design changes and material improvements to the Dukes pumps under a repair station certificate, surely a company like McFarlane could refine the current design.
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This would be great. This part could really benefit from design/materials improvements. Plus the price has become so ridiculous that to OPP would be the same or less costly than a factory part. When that happens, it’s time for a an alternate vendor to get involved.
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In my experience it just frays where the duct is compromised so instead of being torn, it’s just torn and fuzzy…
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The stops set travel limits, they have nothing to do with play/flex within the system’s travel. I’m am glad he discovered this on the ground. It’s conceivable that air loads on the ailerons could cause the same issue without the need for the abrupt movement. -
I agree with everything you’ve said. However, every time OPP comes up, there are several folks that interpret the guidance in ways it was not written. That tells me that it could be better codified.
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You can forgive folks for being confused given the wording of AC20-62E, which clearly states that OPP must conform to approved data.
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According to Ass. Chief council Donald P Byrne’s memorandum, providing an existing part for duplication sufficiently meets the bar for conforming to approved data. http://www.velocolutions.com/FAA-owner-manufactured-part.pdf
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You should be good then for about 300hrs or 6 years, which ever comes first.
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This^^^. Time to pull the belly panel to view and feel the center bell crank actuating the aileron links. If nothing stands out visually, the bell crank can be disconnected from both aileron linkages by removing a single bolt. That should enable you to isolate whether the biding is in the cockpit linkage or in one of the wings.
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The pushrods, links, bell cranks and rod ends all contribute to play/flex in the system under load (it's why we have rub blocks). It's conceivable that if a minimum clearance situation has been created somewhere in the linkage, an abrupt movement might flex the linkage enough to cause interference.
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No risk in telling you to stick with the book. What could we have possibly learned in half a century? Everyone else has covered the simple answer. I would say that temps are the second most important consideration next to terrain clearance. Does your G model run hot in the climb? In my experience, the O360 powered Mooneys run hotter than I would like at max power. Some have no choice but to reduce power to maintain comfortable CHTs. Some say that CHTs as high as 420 in climb are acceptable. If I were you, I would make a decision about what you think is acceptable and manage to those metrics, not some arbitrary "blah blah squared". Climb as rapidly as you can within the temp range that you find acceptable.
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Something was done. Unlikely that this is a lubrication issue.
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Allen, I truly appreciate your efforts. I am ready to support this anyway I can, I also have a spar duct in my hangar. Happy to send it to you as pattern to produce a duct for me. My mechanic and I will conduct additional QC on our end.
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I just looked at my spare today. Mine appears to have cotton cord embedded in the rubber. There is no metal.
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Not a criticism of your technique. Just didn’t want a potential fuel system issue to turn into a trip down a rabbit hole that has nothing to do with hot starts.
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Flap Pump rebuild picture dump
Shadrach replied to TheTurtle's topic in Vintage Mooneys (pre-J models)
Thanks for circling back. That’s great news! It’s funny, I was just thinking about you today while I was on the phone with a shop in Florida helping them sort through a different hydraulic flap issue. I’m glad you got it all worked out. If you get all the air out of the system it should be precisely four pumps to full flaps and hydraulic lockout. -
1959 Mooney M20A questions
Shadrach replied to airbusflyboy's topic in Vintage Mooneys (pre-J models)
Wood wing is not necessarily an issue. You need to find a mechanic that can inspect it thoroughly to verify its condition. Understand that you we are talking about a 65-year-old airframe that is best inspected and serviced by someone that knows and understands the type. Those individuals are getting harder and harder to come by. I would imagine the Don Maxwell has more expertise in this area than just about anyone in the country. -
I should’ve been more specific with regards to flooded starts. My comments were directed at the idea of intentionally flooding the engine after a failed hot start in order to start from a “known“ condition. Significant potential there for things to go pear shaped.
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Scott, I got my wires crossed and confused the issue a bit. My engine will COLD start in cool weather with the mixture full Rich and no prime. It takes several blades, but it works. It’s a handy tool to have if you need to start up and taxi with a dead boost pump. I would not advocate flying an aircraft without a working boost pump. I have never tried it as a hot start procedure and therefore cannot recommend for or against it. However, if Skip says it works, i’m inclined to believe him.
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I find his works acceptably in cooler weather. In hot weather, not so much. I haven’t much thought about why.
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Just to be clear, I’ve never flooded the engine intentionally (nor accidentally for that matter). I’ve seen Mooneys (and other makes) catch fire during a flooded starts. The sheath of my ram air cable is melted from what I suspect was a less than optimal flooded engine start long before I started flying. I once saw an E model at the self service post fire. No major damage but required max before returning to service. We had a Stearman on the field that required paint repair after flooded a hot start. Would have been much worse but he stuck with it until it started and extinguished the fire.
