Thumper
Member
Is anyone able to post pictures of a/their 7KCAB with the cowling off and the components of the inverted oil system visible?
Citabria Inverted oil system
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Thumper
Member
I mainly ask because my 1974 Citabria 7KCAB built by Bellanca lacks any type of Christen components nor the inverted oil system pieces as depicted in the manual diagram... I was under the impression that all Bellanca built aircraft ran the Christen system. My plane was being advertised as having inverted fuel and oil when it was purchased. In trying to understand this whole thing I am now aware that there is an older Champion style system but how would I be able to identify if that is what is on my plane instead of nothing at all before I go roll it upside down and damage my engine when I realize there's no oil pressure? It seems weird to me someone would even buy a 7KCAB instead of a different model Citabria in the first place and then bin the system while retaining the inverted fuel tank which I am able to visually confirm it still has. In place of a big old white slobberpot I have a tiny bare metal air oil separator on my firewall which can be seen in my picture.
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Bob Turner
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Do you have the maintenance manual? It discusses both types.
The Christen is characterized by a big can on the firewall, and a shuttle valve with three ports, from which your oil pump sucks. I can help a bit with that, but you probably have the other type.
Even with a known good system, glance at the oil pressure when you roll. It will go to zero, then right back up. If it doesn’t, roll right side up. Three seconds without pressure won’t hurt.
The Christen is characterized by a big can on the firewall, and a shuttle valve with three ports, from which your oil pump sucks. I can help a bit with that, but you probably have the other type.
Even with a known good system, glance at the oil pressure when you roll. It will go to zero, then right back up. If it doesn’t, roll right side up. Three seconds without pressure won’t hurt.
Thumper
Member
I'll take a look at the MX manual as I believe I got it with some other documents when purchasing the plane maybe even check the logs too. I am almost certain it lacks the Christen system however because I did not see the distinctive big white can on the firewall on either side nor did I see the three port shuttle valve anywhere when I was poking around with the cowling off.
I am perplexed by it because as far as I can tell, my model year Citabria which is built by Bellanca should have left the factory with the Christen setup already installed seeing how my owners manual shows a diagram for the Christen system with the shuttle valve and large air oil separator can.
So now I am just trying to figure out if somehow I ended up with the old Champion system on my engine or if I have a 7KCAB with inverted fuel but no inverted oil! Knowing it won't instantly cause mayhem is a little bit refreshing though, maybe I'll have to go and test it out that way.
Bob Turner
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The airplanes came from the factory with both. Only E2B engines came with Christen (p.7-26) but the Champ system came with E2A and E2B. You need Bellanca Manual #320. 1974 is only the second year for the KCAB (apparently) so yours probably has the pickup in the sump.
I think your aircraft is required to have a functioning inverted oil system to be airworthy. It would take a field approval to remove it.
I think your aircraft is required to have a functioning inverted oil system to be airworthy. It would take a field approval to remove it.
Thumper
Member
Hey bob appreciate the help upon looking at the engine logbooks and the service manual it does appear to be an IO-320-E2B and has the trap door type system rather than the Christen. It's weird how this info is not put anywhere in the POH nor can you really find much info on the Champ system on the internet. What I have found is that some people prefer the Champ system versus the Christen one.
Hi Thumper,
As I underestand it, the original Champion system uses a scavenge pump to collect oil from the engine when it's inverted and to return it to the oil pump via a small separator tank. The scavenge pump and the tank should be on the upper firewall on the aircraft-left side. A scavenge pump, in case you're not familiar with the term, is a pump that is used to collect fluids that need to be returned to a sump or moved to different area that can't get there themselves. The Christen system uses gravity when it's upright or inverted via a valve that repositions itself as the airplane is maneuvered upright or inverted. Someone will correct me if I'm wrong which is always a possibility!
You're right, there are people in the Citabria/Decathlon community that prefer the Champion system though the factory exclusively now uses the Christen system which is now owned by Lycoming so it's technically the Lycoming system.
Parts 21 and 22 in the diagram.
Bart
As I underestand it, the original Champion system uses a scavenge pump to collect oil from the engine when it's inverted and to return it to the oil pump via a small separator tank. The scavenge pump and the tank should be on the upper firewall on the aircraft-left side. A scavenge pump, in case you're not familiar with the term, is a pump that is used to collect fluids that need to be returned to a sump or moved to different area that can't get there themselves. The Christen system uses gravity when it's upright or inverted via a valve that repositions itself as the airplane is maneuvered upright or inverted. Someone will correct me if I'm wrong which is always a possibility!
You're right, there are people in the Citabria/Decathlon community that prefer the Champion system though the factory exclusively now uses the Christen system which is now owned by Lycoming so it's technically the Lycoming system.
Parts 21 and 22 in the diagram.
Bart
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Daniel Hauf
Member
Does anyone know where I can obtain the oil scavenge pump (or equivalent) for my 7KCAB? It was optional equipment, mine doesn't have it.
Salvage yard?
Dan
Salvage yard?
Dan
David Johnson
Member
Don't think there is a scavenge pump. It was always described to me as a simple flapper door that trapped the oil when inverted. The oil pickup is supposed to swing up and down to follow the oil. You won't see any components visually, they are all inside. Get a borescope and try to go thru the drain plug.
Daniel Hauf
Member
There is...it's optional... look at the diagram and in the service /parts manual..
Part 22... pumps oil from the separator back to the sump...
Part 22... pumps oil from the separator back to the sump...
Where does it say the pump is optional?
Does it run continuously or is there a switch for it that gets turned on when doing aerobatics?
Does it run continuously or is there a switch for it that gets turned on when doing aerobatics?
Daniel Hauf
Member
Univair/Bellanca parts manual 7CPM page 129/131 item # 26.
Univair/Bellanca service manual 7CSM page 7-24, Fig 7-6, item 20.
Also page 9-3, Fig 9-1, Electrical schematic. It operates only when inverted and is activated by a mercury switch that can be tested by removing it and inverting it to ensure the pump operates..
I've noticed differences in the publications from Univair through the years and also differences in Bellanca manuals... the post earlier above with the parts diagram has a different part number than the manual I have... mine shows the pump as part # 8110-C as opposed to the above showing 1B5-9...
Dan
Univair/Bellanca service manual 7CSM page 7-24, Fig 7-6, item 20.
Also page 9-3, Fig 9-1, Electrical schematic. It operates only when inverted and is activated by a mercury switch that can be tested by removing it and inverting it to ensure the pump operates..
I've noticed differences in the publications from Univair through the years and also differences in Bellanca manuals... the post earlier above with the parts diagram has a different part number than the manual I have... mine shows the pump as part # 8110-C as opposed to the above showing 1B5-9...
Dan
Trapdoor installed in baffle is not installed by Lycoming, it is a Bellanca mod. This baffle is fitted between the sump and the engine cases after the rest of the engine is built up. The flapper door is seen under the "swivel" section of the oil pick up screen tube.
The swivel section has the outer tube sliding over the inner tube by about 2 inches. (fairly neat sliding fit). When inverted the door falls closed, although there is obviously still some leakage back thru gaps in the baffle.
The swivel action allows the pick up tube to rotate (flop) over to the side to extend the amount of time the pump can pick up oil.
The screen is more of a finger screen than a pancake style found in a road car. This allows the pickup to be close to the baffle.
Kel.
The swivel section has the outer tube sliding over the inner tube by about 2 inches. (fairly neat sliding fit). When inverted the door falls closed, although there is obviously still some leakage back thru gaps in the baffle.
The swivel action allows the pick up tube to rotate (flop) over to the side to extend the amount of time the pump can pick up oil.
The screen is more of a finger screen than a pancake style found in a road car. This allows the pickup to be close to the baffle.
Kel.