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Accumulator
I know that Gmas has talked about this, but my plane has an accumulator. Is that a good thing or a bad thing. Could it interfere with synchronizing? Should I remove it? In looking at it, the hose appears to be chafed, so at the least I have to think about replacing the hose.
We're going over the plane last weekend in anticipation of the annual next month. 
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#2
09-30-02, 06:37 PM
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accumulator
Larry
The accumulator is for unfeathering a prop. It is a pressurized vessel that has air and oil. In the event you need to Unfeather the engine (training hopefully) it will quickly return the blades to their normal operating position. It should not affect sync. Downside is it needs maintenance and it is a fair amount of weight. Check your equipment list and it should tell you. It was an option. There may be a limit set for pressure testing of the accumulator tank. GMAS can probably add more to this. bob
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#3
09-30-02, 11:09 PM
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Thanks
The travel air had accumulators, so I know what the basic function is, on that airplane. Also, you dive to 180 before un-accumulating the prop *SCARY*.
Anyway, I could have sworn that at one point in time or another, GMAs suggested that they were a waste of time, and only really contributed to leaking oil out the back of the airplane, and adding weight that wasn't needed. BTW, this is on the rear engine, only, and there is no accumulator on the front engine, which seems odd. You'd think if they bothered to put accumulators on one engine, they'd put it on the other.
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#4
10-01-02, 08:17 AM
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Prop Accumulators
Larry, the front one is in the nose gear wheel well, on the forward bulkhead. Follow the hose from the front prop governor. The accumulators don't require a hydrostatic test, and they're rebuildable with 'o' rings. I have them, they were standard equipment on O-2's, and I usually have to service them w/nitrogen every 90 days. Its very unusual to have one on one engine and not the other.
Dave 68-11055 "Viet Cong Hunting Club"
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#5
10-01-02, 04:31 PM
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Ahhhh the old accumulators again... a product of OLD technology...
Yep larry they are their... yep they do leak.. yep they need servicing and if they are on the plane.. well at annual you have to spend the money to fix em so they will work... none of this well I never have used it before... thing... smile...
But,.... you notice that Bob doesn't have them on his.. nor did they put the things on later years... that and along with the engine primers that you pull and push... pilots came up with a better way... don't they always... Them old dogs were redunduncy factors... today... if you feather a engine.. you should have know why.. and wouldn't have if it were not necessary... so why are you going to unfeather one...Hmmm.... but, lets just say you made a mistake...(smile) and did it... well without the eletrical system you could move the prop control and the blades would start to move .. the air would catch them and they would start to turn the crank... least that is the idea... but, in fact you can have it un-feather and not crank the engine over.. they will just stall and nothing happens except for the drag... So the better way... well if you feathered it ... again by mistake (smile)... and you didn't have the heavy payload crimping weight taxing accumulators... what would you do.. well you would just touch the starter ... and it would spin the engine... either starting it or with the prop control in the fwd positon.. it would make enough oil pressure to delatch the pins in the prop from spinning it... and the blades would by spring pressure return to their flat pitch and spin the engine just like the acculumators did... ahhhhh... yes it does work.. check out the later POH's.. for their proper unfeathering proceedure... smile... How much do the OLD accumulators weigh... well if you had two of them on a scale they would equal one suitcase full of cloths... ya they are heavy... and just think you are hauling them all over the sky with you... huh.... when your wife needs that extra suitcase for the trinkits and bootie she wants to bring to the meeting... smile... Oh and the engine primers.. they were done away with by using the boost pump... smile.. another good item to put on a skymaster... especially when the battery is dead... and your going to try and hand prop that 210 hp 6 cyc engine.... ahhhhh don't think so... the last guy to try it ... isn't a guy anymore... we now call him fill.... If the battery is dead... go get a mechanic because you don't want to get up in the air anyway.... this ain't no piper cub or champ.... If you try and hand prop it... it will (notice I didn't give any room here) reach out and bite the hand off that feeds it... smile... Check with the local prop shop... do a 337 and cap the outlet off... remove and adjust for the great weight savings... and put the new page in the POH from a later manual... on how to un-feather the engine you didn't want to but, accidently featherd when you didn't want to intentionally feather it in the first place but, that damm instructor made you do it... is a good answer/ saying... we now live better thru electricity.... smile... (P.S. hope kathern is better now... sorry to hear that she is going to see the doctor).... still looking for her reply...smile...
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#6
10-01-02, 06:53 PM
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Thanks
Thanks GMAs. I knew you'd said something about them being unnecessary. I'll talk to the mech about removing them. first I'm going to check the front engine.
The one time I feathered the rear engine, I landed the plane, and when I unfeathered it to start it, I don't think the accumulator played a big difference. I'll tell Kathryn you inquired. I'm sure she has written, but I'll make sure she does.
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#8
10-30-20, 01:03 PM
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Quote:
Based on this, I don't think there's any issue removing them, any more than there would be an issue removing boots from a plane that came with them. Remove them, issue a corrected W&B, note it it the airframe log and you're golden. EDIT: I'm a big fan of accumulators on multi engine trainers, where you feather a prop almost every flight. They make in-flight engine restarts 10x smoother. But on a non-training aircraft, where the only time you feather a prop is because you have to, I don't see the value. You lose the weight of a suitcase for something you really don't need. Furthermore, they are just like a strut - if you don't keep them serviced with nitrogen, they won't work. Last edited by mshac : 10-30-20 at 07:26 PM.
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#9
10-30-20, 04:39 PM
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Accumulator
mshac. Since the accumulators are optional, and as long as the WT&BAL is updated there is no problem with removing them.
Bill Story '65 C337 Owner, pilot and A&P
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#11
12-07-20, 05:42 PM
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I believe it is implied that it is optional, since some were built without them. We are having an A&P look at it, add it to the Mx logs, and probably put a "notice" in the cockpit that they are not installed. Makes sense to not have them, just trying to do it the right way and stay within the certification
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#12
12-07-20, 10:37 PM
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Look in the type certificate data sheet, if its required it will be listed here. If its not listed, you may remove them. Look for the weight and arm in your T.O. 1L-2A-5 Technical Manual. Item number D-1 for the rear accumulator, 5 lbs at station 207, and 5 lbs at sta 35 for the front accumulator, item A-1.
Removing the accumulators is no different from removing the ARN-83 Receiver or the APX 64 receiver transmitter.
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#13
12-08-20, 04:00 PM
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Quote:
There can also be things listed in a TCDS that you *are* allowed to remove. For example, the TCDS for a Cessna 340 lists 6 seats, but the equipment list in the POH makes it clear that only one is required for flight. Cessna didn't start providing equipment lists until the mid 70's. You won't find them in the old "Owner's Manuals." They don't start showing up until you have a "Pilot's Operating Handbook."
__________________
1969 T337E
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#14
12-08-20, 08:23 PM
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Jim C, we're not talking civilian 337's here, we're talking O-2A's, different animal. The M-337B has a different paragraph in the TCDS, same as the 337G or H models. The O-2's have a document called the dash 5 that I referred to earlier in this thread. It allows the removal of certain installed items and still allows the airplane to perform its mission. For example, it allows the removal of wing weapon pylons, it allows the removal of M-16 rifles. It does not allow the removal of tires, brakes and other required items.
There is no pilots operating handbook or equipment list like you will find for a 340 for the O-2A or B. If you go to the FAA Master MMEL list, you can even operate under certain conditions fly legally without meeting the minimum equipment for basic VFR under parts 23 or 91. For instance, you could legally fly without operating fuel quantity gauges or magnetic compass. If you look at the TCDS for a 337D, you will notice that prop spinners and bulkheads are required, but for the O-2A's built at the same time, they are not.
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