New member in Montana; a couple of questions...

longez

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Aug 1, 2020
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I spoke with Clay Phelps of CP Aviation in Santa Paula CA over the weekend; he's been doing the annuals and maint on the 7KCAB I'm interested in buying. He's sending me copies of the logs, but the thing he doesn't particularly like about the plane is the OE inverted oil system; he much prefers the Christen or Raven system. Apparently, Clay thinks it's necessary to pull the sump every few years and check/clean the flopping baffle. Is this a reason to not buy this bird, or something that should be changed "soon", or is he worried about nothing? The current owners don't do acro in it, but I will.
 

BB57

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Feb 20, 2020
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I spoke with Clay Phelps of CP Aviation in Santa Paula CA over the weekend; he's been doing the annuals and maint on the 7KCAB I'm interested in buying. He's sending me copies of the logs, but the thing he doesn't particularly like about the plane is the OE inverted oil system; he much prefers the Christen or Raven system. Apparently, Clay thinks it's necessary to pull the sump every few years and check/clean the flopping baffle. Is this a reason to not buy this bird, or something that should be changed "soon", or is he worried about nothing? The current owners don't do acro in it, but I will.
It depends....

If you ask ACA they'll tell you to get rid of the Champion inverted oil system. But they also won't support wood spar wings. I have a hard time not viewing some of their positions as being monetarily motivated.

Objectively, the Christen system is better, and it's enough better to make a difference if you do extended inverted flight or negative G aerobatics. Otherwise, it's a distinction without any meaningful difference.

The Champion system uses a baffle in the sump with a door that closes in inverted / negative g conditions. The oil pickup is a "clunk" tube that then drops down onto the baffle which is now the "floor" of the inverted oil sump. There's a firewall mounted breather and a shuttle valve that controls which way things flow. It's a very simple system. The manual says the Champion system is good for 2 minutes, but it also notes you need to watch the oil pressure. That's because the oil returning to the sump will be on the wrong side of the baffle and once the oil on "top" of the inverted baffle is gone, the oil pressure drops. In addition, I suspect that 2 minute rating is based on 8 qts of oil in the sump and operating with less oil in the sump will reduce the time that oil pressure can be maintained. Power settings also obviously make a difference in terms of the rate the oil is being pumped out of the sump.

My 7KCAB tends to spit out anything over 6.5 quarts in the winter and anything over 6 quarts in the summer. As a result, I normally fly with 6-6.5 quarts, so I won't even consider pushing the 2 minute limit. But then again, the demands I'll make on it are the occasional slow roll, split S or Immelman. The consensus I've perceived from users of the factory system is that 45 seconds is a pretty reliable number for inverted flight with the factory system before a drop in oil pressure occurs and, for me, the Champion system more than covers the need. If I owned a Decathlon and did lots of inverted and negative G maneuvers, I'd definitely prefer the Christen system.

Inspection wise, originally Champion recommended checking the baffle and pickup every 400 hours. However, looking back at 53 years of logs and 2 major overhauls (both around the 1600 hour mark) on my aircraft, and after reading reports from a number of other 7KCAB owners with the factory system and overhauls in the 2000-2400 hour range, I don't think the inspection every 400 hours is necessary and I can't find any evidence that one was ever done on my aircraft in about 3400 flight hours. The owners with 2000-2400 hours since overhaul and inspecting the system at overhaul have reported no issues with the baffle and only some minor rubbing on the oil pickup.

In my 7KCAB's case I suspect the 1600 hour or so overhauls had more to do with its history towing banners, and long periods sitting idle, than with any loss of oil pressure when inverted or any issues with the baffle or oil pickup.

In short, I don't see the Champion factory system as a deal breaker (it can be converted to the Christen system via an STC if you want it), nor even as an issue, depending on how you plan to fly it.
 

Bob Turner

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Apr 4, 2018
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If the factory put the Christen system in, you would not need an STC. Mine has the Christen, and since it is in the maintenance manual and supported by the factory, I suspect it is in the TC.

There is this pesky O ring in the sump plug that needs to be replaced every ten years or so - can be tricky if you don't know what you are doing. It is a Lycoming part number, and realy expensive ffor a simple O ring. Plug should have been machined for two O rings.
 

longez

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Aug 1, 2020
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8S1
Thanks gents - I'll live with the Champion system for a while and see how it performs. I never liked hanging from the straps for sustained periods of time, or enjoyed eyeballs out g's. It's going to be a period of adjustment for me with a certified plane, I'm used to simply modifying at will.

BB57, the O-320-D3G and IO-360-B1E in my EZ's are also both happiest with 6 quarts in the sump; any more than 6 is puked out in an hour or two. I'm having CP Air check with ACA to ensure spades can be installed on the metal wings; I'm pretty sure the pre-buy will come out clean, but it would be nice to have CP install them while the plane is still in Cali - not sure anyone at my airport has worked much on a Citabria.