View Full Version : Warrior - Oil
1st Aug 2012, 12:18
The Warrior at our club is a lovely aircraft, but it seems that lately every time I check the oil it needs some in. As far as I know, it doesn't typically go further than a couple of hours away so am I being over the top in my checks?
My checklist states that the oil should read 6-8qts on the dip stick, however just recently it seems rare that there's more than 5-5.5 in it. The last time I flew it the engine was still warm, so had just been flown and when I checked the log in the clubhouse it had only been away for an hour. I checked the fuel pump log for the aircraft and no oil was logged as taken.
So, how low would you let it get, and how quick, in your experience, does it typically disappear? Are fellow club members simply not checking the oil, checking it and flying the plane anyway or filling it, not logging it and it's burning away?
There have recently been occasions where I've been the only one at the field, nobody to help, oil needs topping up and the oil is stored behind locked doors so it's beyond reach. Would you fly?
1st Aug 2012, 12:38
If you fill a Warrior to 8 quarts the oil will go down quite quickly to around 6 quarts which is why most operators use 6 quarts as the maximum. I think the book for the engine specifies a minimum of 2 quarts, plus half a quart for each hour you intend to fly.
1st Aug 2012, 12:45
Yes, engines will operate adequately at some level lower than the minimum, but this should be considered "abnormal" and not done casually. If you are checking oil on a warm engine, you can expect a lower reading, as some of the oil is still up in the engine. Should be half a quart difference or so.
Some engines seem to find their "happy" quantity, ans as you get to know a particular engine, you will get to know it. Both my engines are "happy" at a little less than the maximum. My O-360 is very happy at 6 quarts indicated. If I put in 7, it will reduce itself to 6 shortly, then remain their for some time.
Air cooled engines consume oil at a much greater rate that today's car engines, so don't compare. Oil is a consumable. The Tiger Moth I fly occasionally, is literally "top off the oil, and check the fuel".
If the engine you're dealing with is high time, it'll be burning more oil. That's just the cost of running high time engines. Aside from the cost of the oil, it's not so bad - a constant oil change!
If the engine specifies 6-8, do not operate it at less than 5, but ask the maintainer why it needs so much oil, they should have some explanation. Keep a few quarts of your own, so you don't have to worry about the supply being locked up. Never use non aircraft engine oil in it! Just don't fly.
1st Aug 2012, 13:55
You need to find out the exact engine type installed (e.g. O-320-XXXXX) and get the manual for the engine, which will specify the minimum oil level.
There will also be a maximum level but as Whopity says, usually filling it to max just causes the engine to blow out the extra out of the breather. For example mine is 6qts min and 12qts max, but anything over 10 is quickly lost, so I run it between 8 and 9.
The engine manual will also specify maximum oil consumption. If it is worse than this then the engine is not airworthy so the aircraft cannot be flown. However this figure is scarily high - of the order of 1qt to 2qt per hour ;) If you are burning anywhere near that figure then I suggest you stick to nice flat countryside and do the national lottery regularly :) What is it actually burning? 0.1qt/hr is about right for a good engine, 0.3qt/hr for a somewhat shagged one, and those figures are for the 6-cyl IO540-C4. Yours should be less.
1st Aug 2012, 14:07
Some great pointers there, thanks.
I need to look up the exact engine and its manual, then. Unfortunately I haven't flown it for a land away for a while, so don't tend to look at the oil level after the flight! Next time I'll remember to do so.
I may just keep some of my own oil, good tip. I pay a wet rate so it should be 'all in' really but at least it'll mean I can still fly if there's nobody around and it's thirsty.
1st Aug 2012, 14:09
From the O-320 and IO-320 Series Lycoming operators manual:
All Models: Oil sump capacity 8 US quarts, Minimum safe quantity in sump 2 US quarts.
Consumption -A & -E series @<hidden> .67 qts/hr, @<hidden> ..37 qts/hr, @<hidden> .33 qts/hr
Consumption -B & -C series @<hidden> .72 qts/hr, @<hidden> ..4 qts/hr, @<hidden> .35 qts/hr
You sure would not find taking off with an engine at the minimum safe quantity plus consumption allowance. I'd be very concerned about overheating it....
Big Pistons Forever
1st Aug 2012, 14:43
Excessive oil consumption is the engine telling you something is wrong. Like others have said most engines will, if filled to the maximum value vent the top quart fairly quickly and then the oil level will stabilize and reduction in oil level will reflect the actual oil that the engine is burning which is typically in the range of one quart every 5 to 10 hours. For the average Lycoming keeping the oil level at 5.5 to 6.5 quarts seems to be the magic number. On mine I add half a quart when the dipstick reads 6 Quarts, although it probably would not make any difference just to add a whole quart at the 5.5 mark.
Having said all that the problem with club or group aircraft is keeping an accurate oil log. So is the reason that the oil is low is because nobody bothered to add any in a long time, or is it because the engine is burning a lot ? That is the question. I suggest you talk to the engineer looking after the aircraft. If it is a group aircraft then perhaps you should get the group members together and have a discussion about managing oil levels and logging oil consupmtion.
Also while high oil consumption is not great, it is usually not indicative of imminent failure. What is indicative is a sudden dramatic increase in oil consumption which is why logging oil added is important.
I once had an engine failure in a Piper Navajo shortly after max weight takeoff near dark from a short unlighted strip in the mountains. I had no choice but to go back and do a minimums NDB circle to land on one engine approach to get into the airport I had just left :ouch:
It turned out that 2 pilots had put a total of 6 :eek: quarts of oil in that engine in the previous 4 hours of flying and could not be bothered logging the oil added, or telling me or maintenance :mad:
That engine was screaming that it had a problem but the two clowns flying before me were oblivious............
1st Aug 2012, 15:03
I'd be very concerned about overheating it....
I've been told that unless virtually zero, the lower the oil, the cooler the oil. This is because a greater percentage of the total oil is being cooled and each unit will be passed through the cooler more often. However, if the oil level is excessively low firstly it will break down more quickly and be less able to do its job of protecting the moving parts of the engine and secondly, there is a greater chance of the oil pump inlet becoming exposed.
1st Aug 2012, 15:47
This is because a greater percentage of the total oil is being cooled and each unit will be passed through the cooler more often.
It will also pass through the engine more often. So somehow I don't buy this argument.
1st Aug 2012, 15:54
It's an interesting theory but I've never noticed what I would expect to be a really obvious oil temp variation.
Without thinking very deeply about it, I think the theory might partly hold for an infinite-sink oil cooler i.e. one which instantly cools the oil down to the OAT regardless of anything. But oil coolers are not infinite; far from it, and if they were they would be useless because the oil would be far too cold to flow
I had a Warrior (161) for seven years. The oil usually sat at around the 6 mark and I never ever had to put more than one litre in it at any one time. Even after a complete overhaul, it was still the same.