Magnetic plug shipped in tailrotor gearbox
OPERATION & MAINTENANCE
This section is definitely a work in progress and is only in it's very early stages. However, there is already a bit of information in here that might give a builder a tip or food for thought. As such, I've decided to include it in the website. I would sincerely appreciate any tips and feedback from other owners who already have an operational machine.
For lack of a better place, I thought I'd start writing down some of my thoughts regarding operational issues once the craft is flight ready. Obviously this is jumping the gun a bit for me, but I wanted some place to start recording this information. It is not meant to be a replacement for the POH, (Pilot's Operating Handbook) but rather a supplement to it.
From a mainentance standpoint, I believe a guiding adage should be "If in doubt, throw it out". A helicopter is no place for marginal components or quick and dirty repairs. The fact that one may question whether a part is still useable leads to a simple answer ... NO, it's NOT! I've talked to one helicopter maintenance engineer who told me that one of the certified shops he worked in had the policy that no bolt, nut or washer would ever be re-used. Once it was removed, regardless of it's appearance it was immediately thrown in the garbage and a new replacement used. It is virtually impossible to tell by eye if a bolt has been stretched or suffered stress ... why risk an entire machine over a $0.50 (or less) bolt.
FIRST IMPRESSIONS
I only have about an hour of hover time in my machine at this time. However, that is enough to form an initial impression of the controls when compared to an R22:
Collective: Mine is now balanced with the trim spring for hands off operation. Basically it feels and reacts exactly as I would expect it to ... in other words, I'm not thinking about it but rather just using it. What more can I say except that one needs to adjust their trim arrangement to achieve this goal.
Cyclic: Initially it took me a bit of getting used to as there is a bit of delay or lag on control inputs. When reacting to a wind gust or other excursion, I find that in the R22 I can input a fairly rapid correction and then try neutralize the cyclic immediately. This seems to work fairly well for me. On the Safari I found that I had to input the correction and then hold it there for a bit before returning the cyclic to neutral. Initially I had to be conscious of this but it quickly became more of a reflex. The other thing I found was that in a hover taxi if I let the machine slow down then it would rapidly want to come to a stop. I had to recognize this slowing tendancy and consciously increase the forward cyclic.
Pedals: These cause me a bit more of a problem. The left pedal feels exactly like what I would expect but the right pedal is extremely heavy. Initially I actually thought the right pedal was on the stop until I was told to keep pushing it (and to push even more). At this time I have to keep my heels off the floor in order to consciously think about adding a lot of pressure to the right pedal. I'm sure this will change with time but I can see that it won't be like the R22 where I can just use toe pressure most of the time.
Governor: Mine is now working fine and I'd highly recommend this when someone is first transitioning. There are enough other subtle differences that one is getting used to and the throttle is just one more added workload item. The governor allows one to concentrate on the flight controls exclusively. Later on I will start playing with governor OFF operation in order to get used to that mode and to set the final adjustment on the correlator. For now I'm leaving it ON.
OPERATION
The Pilot Operating Handbook (POH) contains most of the basic information that a qualified pilot would require. However, there are a few issues that fall outside of it's scope such as the initial testing.
One aspect that will need to be checked fairly soon after the craft is starting to be flown at altitude is the autorotation capability. Although the blades may be rigged according to documentation, it is still necessary to carefully evaluate whether the craft can maintain Rotor RPM in an auto. Another builder was recently going through this phase and consulted with the factory. The response is summarized here:
- This should be performed when the ship is light (~ 1/4 fuel)
- Initial tests should be done with plenty of altitude (1,000' to 1,500' AGL)
- Rotor RPM should remain at 450 (90%) or above
- If the Rotor RPM can't be maintained then both pitch links will need to be adjusted out one or two turns for more negative pitch
Fuel level and 2/rev vibrations
Because 2/rev vibrations generally tend to increase with lower fuel levels (especially below 1/2 tanks), it is normal to start the Safari with full fuel tanks or at least in the upper half. I find this extremely wasteful of performance and believe that owners should try to reduce the 2/revs as much as possible. When doing short flights (perhaps 1 hour or less) there is no requirement for more than 1/2 full fuel tanks as this gives enough fuel for the flight plus reserve (20 minute mandatory but more than 30 minutes in reality). The extra 14 gallons to go from 1/2 to full tanks is just a dead weight of approximately 84 pounds and will impact performance. No helicopter pilot I know would consciously and consistently carry around 84 pounds of unnecessary dead weight, so why do we want to carry around that much fuel that is not required? The other aspect is that a full fuel load when flying with a passenger can easily put the craft over the gross weight limit.
MAINTENANCE SCHEDULES
There are a lot of parts and fluids that need to be on a maintenance schedule which will be based on calendar time, operational hours and/or a combination of both. Although CHR provides the details for the transmission oil change interval, that's about it and I didn't receive any other kind of additional reference material from them. Thus the owner needs to create their own schedule ... it would be nice if someone in the Safari community were to publish their schedule so it could be used as a foundation for all owners as the source and reference of these items come from a wide range of manuals and literature.
The ideal solution is to create a computer spreadsheet that automatically lists the various times remaining and calendar intervals. Unfortunately not everyone has a computer readily available at the location where their craft is hangared. In Canada we have a requirement to maintain an aircraft journey log which records all the flights / hours for a craft and must be carried in the craft whenever it lands at a point other than it's departure point. I've seen a simple idea where business size cards are created which have a simplified list of items like next oil change, next annual, etc. and are inserted into the journey log. Thus after every flight when one is filling out the log they can also check when the next maintenance interval is.
In addition to the routine maintenance items, I
need to create an annual inspection checklist. Luckily there is a
generalized prototype available that can be modified for the
specific craft. Ideally, the annual can be made to coincide with
some of the routine calendar based maintenance items so it can
all be done at the same time. Besides the actual inspection, for
Canadian craft CAR
625(C) lists some of the not so obvious requirements:
ELT inspection: every 24 months
Compass swing: every 12 months
Transponder / Encoder calibration: every 24 months
Altimeter calibration: every 24 months when operated in "transponder
airspace"
ENGINE OIL
This is the lifeblood of the engine as far as longevity goes. I know there are some people who go long past the recommended change intervals and also just use whatever is handy ... that's not my approach. Although oil isn't cheap, I think of it as a cheap insurance plan to try prevent having to do an overhaul which would be much more expensive, time consuming and inconvenient. The primary reason for doing oil changes is that the oil picks up contaminants, both metallic from wear and acidic combustion by-products that are harmful to continued operation. Hopefully one can't actually see metallic particles, but the discoloration of oil is an obvious indication of combustion by-products.
I have a full flow oil filter (versus just an oil screen) and the recommended oil change interval is 50 hours or 4 months. Initially, I'll be doing changes much more frequently than that (something like at 15, 30, 50 hours) since I do have concerns about metal particles during break-in. I'll then switch to the 50 hour / 4 month intervals, but I don't believe in pushing these limits. Note that similar to an automobile, the oil should be changed when it is hot in order to try get all sludge-like deposits within the system into suspension.
As to the actual oil and brand: During the initial 50? hours, Superior recommends only straight mineral oil and depending on temperature, I'll probably be using AeroShell 80 or 100. After that, I'm tempted to use just a straight weight ashless dispersant oil, such as AeroShell W80 and W100, when the weather is above freezing. During the winter when there are wide variations in temperature around here, I'll probably switch to 50-100 multigrade ashless dispersant oil such as AeroShell Multigrade W15-W50. One of the more interesting oils is Exxon Elite and they have some very interesting articles on their website that describe why their product has advantages over others.
Update: For my initial operation I'm using AeroShell 80 mineral which appears to be the recommended choice when operating between at an ambient temperature between 30°F and 90°F. AeroShell 100 mineral is recommended for temperatures above 60°F.
Oil Filter
I have a replaceable oil filter adapter and I think that is much more preferable than an oil screen on the Safari, especially since the screen in the sump is removed during conversion. There are getting to be a few more alternatives on the market, but I'll probably just stick with the Champion CH48110[-1] filters that came with my engine for now ... perhaps someone with more experience will be able to tell me if there is any advantage to installing the longer CH48111[-1] filters since there is room available for them. The filter will be changed at each oil change. Note that normal automotive practice is to wipe a little oil onto the gasket before installation but that the preferred aviation practice is to use a little bit of Dow Corning's DC-4.
Another unique aviation practice is to cut the filters open after removal and inspect it for any signs of metal. There's an interesting article here on doing this and how to use solvent to release any particles from the filter. The other more traditional method is to cut and unroll the filter element then inspect it ... I know I've seen some good pictures on this and I'll add the link when I find it again.
I'm led to believe that not all oil filters are the same when it comes to having a check valve. This isn't a problem when using a straight adapter in the Safari (i.e filter hanging vertically downwards) but could make a difference on an angled adapter ... if the oil were to flow out then there would be a slower startup oil pressure and with the engine off the dipstick would read slightly higher than the actual useable oil. I'm not sure what the effect would be from drain-down of the oil cooler lines ... hmmm something to think about.
Oil Additives
The only additive that I would consider using is Avblend. I've read many articles on this product and they all seem to indicate that it has benefits in preventing rust, wear and sticking valves. I'll probably use this with the straight mineral oil during the break-in period and might continue to use it with the straight weight oils. I don't believe it's use is relevant if one is using Exxon Elite which has it's own additives for many of the same objectives.
Tip: An interesting tip I picked up on the RV website was to only add 1/2 can of Avblend during the oil change and then the other 1/2 at 25 hours (assuming 50 hour oil change intervals). Obviously this will vary according to oil consumption, but basically it is to prevent dilution near the end of the oil change interval. Perhaps 3/4 - 1/4 might be a more appropriate ratio.
I am now aware of another oil additive. Although I have no personal experience or feedback about it, I'm including the reference to CamGuard here in case someone else wants to do more research.
Oil Analysis
I still haven't decided whether I'll be sending oil samples in for a full lab analysis. While this sounds like a good idea, it just adds to the operational expenses and I haven't heard good arguments both ways. Perhaps I might just keep a sample from each oil change and that way if I suspect a problem I can then send in multiple samples to see if there is a trend developing. I do think that I will cut the filters open at oil change time and inspect it for metal particles. The only extra tool required is a can cutter and a bit of time to open the can, unroll the filter and then inspect it. I have heard good things about the can cutter available from Sacramento Sky Ranch.
Although their use has been questioned by some people, it is possible to add a magnetic plug in the drain of the oil tank where it can pick up any ferrous metal that accrues in the oil. Even if the plug is not of the wired chip-detector style with an indicator lamp, it can be inspected during an oil change to see if there is any unexpected ferrous metal. Obviously these plugs cannot detect and collect non-ferrous metals such as aluminum, brass, copper etc.
Interesting side-note: I have seen the results of an engine that lost it's oil pump gears just before TBO. When the oil screen was removed, it was absolutely full of fine metal particles that looked like the pile one sees under a bandsaw after cutting metal ... not a pretty sight and the engine obviously required a full overhaul.
Oil Separator
Piston aircraft engines are known to use a bit of oil and most of this comes out of the vent tube as an extremely fine mist. In the Safari, this venting is from the oil tank. Oil separators are available which try to operate by separating this mist into water vapour and liquid oil, with the oil being collected and returned to the crankcase or tank. I have read reports where owners have seen a considerable reduction in the amount of oil used and this is attributed to the use of a separator.
I added another tapped hole into the cover plate on the oil tank with the express purpose of being used as an oil separator return line. However, now that I've had a lot of time to reconsider this, I've decided not to install an oil separator at this time. Unless the oil separator works absolutely perfectly, it will be returning both the oil and some moisture (including contaminants) back to the tank. However, the moisture and contaminants are exactly what one wants to completely expel from the system. I've decided that saving a few quarts of oil versus the expense of a separator and the potential return of contaminants is not the way I want to go.
Cold Weather Preheating
We get some cold weather around here (occasionally -40°F = -40°C) and there is a need for some kind of preheat unless the craft is kept in a heated hangar. There are some interesting articles on the Tanis and Reiff websites about cold engine starting and how at -20°F (-29°C) there can be an interference fit of various parts rather than the required clearances. Definitely not a good way to start an engine and expect any kind of service life. With a heated hangar, we found that we could roll out R-22's in -20°C (-4°F) and start them without any problems but we were very careful to do the full DI in the hangar, roll it out and then immediately start it up before it could cold-soak. At these temperatures, without a heated hangar I believe it is mandatory to use something like the Tanis or Reiff preheat systems both on the cylinders and on the oil tank. Note that most of the local flying clubs and training facilities around here limit their operations to temperatures of -20°C and above ... survival becomes a serious concern if one has to set down off airport at these kinds of temperatures.
Pre-Oiler
If an engine has been sitting a long time, such as during construction, the oil will run down from it's various galleries and any surface film will become extremely thin. Preservative oil will help prevent this as it is extremely tenatious in it's ability to cling to various surfaces. Since the worst wear condition will be right at startup, the best solution is to use a pre-oiler before startup. This is an external device which essentially acts like the oil pump to circulate the oil under pressure. I've heard of two ways of doing this: a fancy electrical pre-oiler which can optionally be permanently installed and a cheap homebuilder's solution. The homebuilder's solution is to partially fill a sealable pressureable container with oil, connect the outlet of the container to the engine's oil supply line and then use an air hose to apply pressure to the container thus forcing the oil into the engine. Interestingly, the Lycoming procedure to pre-oil a pickled engine is to remove the plugs and then use the starter to spin the engine until full oil pressure is obtained.
GREASE
The pedal assembly and the cyclic / collective system have several grease fittings, but there is no recommended grease in the CHR documentation. I did a bit of reading on this trying to figure out what was the appropriate grease to use. Since I'd painted some of the control assembly sliding surfaces with Perma-Slik G® which contains molybdenum disulphide, I figured it was probably a good idea to use a grease containing MoS2. From the reference material I had, it appeared that Shell 17 / Royal 64 was a good solution. Further investigation indicated that Royal 11MS had better water resistance and load carrying ability. As a result, I'm using Royal (Royco) 11MS manufactured by Anderol.
I need to find out what grease that CHR has used in the mast for the grease fitting just above the swashplate. There is a very wide variety of additives and it is not a good idea to mix different types of grease.
Similarly, I need to find out what grease or oil was used in the main and tail rotor grips.
TRANSMISSION / GEARBOX GEAR OIL
The CHR transmission document recommends the use of 75W-90 gear oil in the transmission, but doesn't specify a recommended brand. In talking with other builders and the reading that I've done, it would appear that Amsoil Severe Gear 75W-90 is one product that has proven to work well and also to reduce operating temperatures. This is a synthetic extreme pressure lubricant. In doing some research, there are also some very interesting (and expensive) lubricants that have been developed for auto racing but I don't have any first-hand experience or know anyone who has tried them in a Safari.
Update: Normally I don't like ordering products through private dealer networks rather than stores. I was talking to an Amsoil dealer at a trade show and managed to get a case of SVG 75W-90 at the commercial rate. I was surprised that even with the shipping it ended up being fairly reasonable. I'd definitely be willing to work with this dealer again.
The instructions that accompanied my transmission
state that the oil should be first changed at twenty minutes and
every two hours thereafter until twenty hours of operation; after
that, the interval is fifty hours. Thus there will be twelve
changes to make it over the hundred hour mark (actually to 120
hours). I've been told that it takes just over 3/4 of a quart to
change the transmission oil (I'll update this after I've done my
own testing) and the tailrotor gearbox takes about 1/2 cup.
Unless one has a good local supplier of the oil they're using,
they may want to look at purchasing a full case. After the break
in period, I'll also be trying to align my engine oil change
intervals with the transmission change interval ... just makes it
a lot easier for me to do it all at once rather than separately.
Update: I used just over 500 ml or one pint to fill the main
transmission. There was a slight addition after the oil fully
settled so this is not an exact amount yet. It is also dependant
on how long a drain line that one installs.
When installing the tailrotor gearbox, I found that I had to remove the oil drain plug to remove the gearbox without disturbing the shaft. When I drained the shipping oil I was surprised to see a few visible metal particles in the oil even though it had been drained cold and the never run except for the obligatory rotation to verify everything was smooth. Needless to say, the oil in both gearboxes will be changed before any powered operation.
Gear Oil Separator
Because of gears running in an oil bath, there
will be a fair amount of oil mist within the transmission. In
talking with various owners, it seems like transmission will find
it's ideal oil level (between 1/2 and 1/3 of the way up the sight
glass) and the excess oil will be expelled from the vent tube in
mist form. Obviously this is a mess that has to be cleaned up
afterwards. I am aware that one ship has installed an oil
separator on the vent line and it appeared to work quite well.
However, I'm not sure if I like this approach as it doesn't allow
the oil level to settle at it's ideal point ... perhaps if the
separator was used just as a catch can without a return line then
it might be more appropriate. I'm going to first try just using
the high vent position and see how that works.
Update: The high vent position seems to work fine.
Chip Detectors
It is normal for new gears to shed a small amount of metal slivers or chips. Consequently, CHR recommends that the transmission and tail rotor gearbox chip detectors are not installed until after the initial break-in period. While this will prevent false chip lights, it can also be a little disconcerting as there will be no warning of potential problems. The magnetic plug that is shipped with the transmission and gearbox is actually a stronger magnet than the chip detectors and can be manually checked even between gear oil changes.
Magnetic plug shipped in tailrotor gearbox
How long does one wait till changing from the magnetic plug to the chip detectors? The CHR transmission document suggests 100 hours. I talked to one builder who changed his plugs at 80 hours since there were no more chips on his magnetic plug. During the next 75 hours he received no chip lights (false or real).
Hot Change Procedure
In addition to getting rid of any contaminants, part of the gear oil change process is to flush any small chips. The only effective way to do both is to change the oil while it is hot. The following procedure was described by Mark Richards to another builder and has worked quite effectively for him:
Now that I've had a chance to change the transmission when the oil is hot, I can see how difficult the above procedure can be. One of the things that you have to be very careful about is that the drain plug is right above the clutch and not that easy to access ... if one allows any oil to drip into the shoe area it will result in a change to the clutch engagement. One needs to be very careful to catch the oil coming out with the plug (an ounce or two) and it also helps to have a shop towel already lying on top of the clutch shields in case there's any spillage.
Tip: I have received a tip that one should vent the drain tube after they have changed the oil in the transmission as any air that is trapped in here will cause the oil to foam. I would assume that eventually the air would bubble out, but if one is following the hot change procedure there probably wouldn't be enough time for this.
Tip 2: I use a one pound coffee can to collect the oil out of the drain tube. By using a piece of safety wire through small holes at the top, I can just leave the can in place while I do other tasks and let all the oil drain out.
Tip 3: I tried using my vent cap to fill the transmission and it is an extremely slow process. I could add a small air vent tube inside the vent tube to speed it up. However, I was shown a much better method by an experienced owner. A suction pump makes short work of filling the transmission through the drain line. Basically the pump is filled with fresh oil and then it is attached to the drain hose (note one needs to check the diameters and may need to machine an adapter). Pressing the pump handle will then inject the fresh oil ... quick and simple. Great tip ... thanks Maynard. In my case, the pump I got was 500ml which is just about 2/3 what the transmission needs ... it really would be nice to find a slightly larger pump.
Tail Rotor Gearbox
I don't have any specific information on the oil and change intervals to be used for the tail rotor gearbox. Unless I receive different information, I'll be using the same oil as in the main transmission and the same change intervals. Since it has a much smaller fill hole and capacity than the transmission, the suction pump really isn't suitable for filling it. I use a large bore syringe which works well and I suppose a small funnel would also work fine.
FUEL & FUELING
100LL versus Auto Gas
With the price of fuel, one is always looking for ways to make it a little more affortable and even with "Road Taxes" auto gas (mogas) is usually cheaper than 100LL and it's certainly more generally available. Although it's tempting to try using mogas, there are several potential pitfalls:
Only mogas that is known to be ethanol (alcohol)
free should be considered since these components can
cause swelling of O-rings and other nasty effects if the
whole fuel system wasn't designed for their use. Another
side effect of alcohols is that they're hygroscopic,
meaning they'll readily absorb water from their
surroundings and it won't be visible. If there is any
doubt, then there are testing kits available from most of
the normal aviation suppliers to determine if there is
alcohol in the fuel. Note that EVERY
batch should be tested since there is no guarantee that a
refinery won't change it's blend over time or that the
wholesaler hasn't had to do some kind of fuel swap and
that a particular batch actually came from the same
refinery.
Mogas has a wider range and typically a
higher vapor pressure rating (RVP) than avgas and this
may lead to vapor lock or fuel percolation and makes
carburetor icing more likely. These effects can be
magnified if the fuel lines are run near a source of heat
or if they contain sharp bends. Note that the supplied AN
fittings in the Safari's fuel lines are of the type with
a 90° internal sharp corner and should be replaced with
fittings that have a smooth radius such as on Aeroquip
and Stratoflex hose assemblies. I'm not sure where to get
these radiused fittings for clamp on hoses, but perhaps
the fittings used in aircraft vacuum systems might be
suitable. Obviously, hard lines can be bent as required
if straight fittings are used.
When plumbed as shown in the Safari construction prints,
the fuel lines from the two tanks join in a T fitting
just before the fuel shutoff valve. I have not seen a
standard Y fitting that would reduce this sharp corner,
but it would be relatively easy to machine one up that
had essentially a straight through path and another path
that joins at a shallow angle.
The other 90° internal sharp corner to be concerned
about is in the fuel shutoff valve. If it is plumbed as
shown in the Safari construction prints, the fuel enters
from the side and in the ON position makes a 90°
downwards transition across a very sharp edge. I believe
it is possible to to change this such that the ON
position would be straight across, but it's been a while
since I looked at this and can't remember the specifics.
I also believe there is a two-port on/off valve that
would be a drop-in replacement that has a straight
through path.
Depending upon the compression of the
engine, it may not be possible to get a high enough
octane rating in common mogas to prevent detonation. My
engine has an 8.5:1 compression ratio and is rated to be
run with 91+ octane mogas, leaded or unleaded, after the
break-in period is complete. Engines that use 9.0:1 and
higher compressions will likely have detonation issues on
straight mogas and possibly even with a blend of mogas
and 100LL. I can't make any recommendations about other
engines, other than to be very cautious when
experimenting with alternate fuels and to be extremely
careful to prevent detonation.
The tetraethyl lead in 100LL avgas has a
lubricating quality and thus 100LL should be used during
the initial run-in of an aviation engine. For how long
I'm not sure, but the XP-360 manual indicates that the
pre-shipment run-in is long enough ... seems a little
short to me. If one is using unleaded mogas fuel then
they may want to consider occasionally mixing in some 100LL
avgas for the lubricating properties.
Additives
I've heard second hand reports of people using TCP as a lead scavenger to help prevent fouling the spark plugs. Another alternate product is Decalin RunUp™. Unless I experience this kind of problem, I won't be using this product or any of the alternatives.
I've also heard of people using Marvel Mystery Oil as a fuel additive to try reduce exhaust valve sticking. Again, unless I experience this kind of problem I won't be using it.
There are also octane enhancing additives that can be used in mogas to raise the octane level a couple of points. While these have been shown to be effective in automotive applications, they're also relatively expensive products and one more consumeable item for the owner to stock and worry about ... it's probably cheaper and much easier to just use 100LL.
Re- Fueling
Obviously this is dependant upon where one is doing this. If one is at an airport then one is probably using a pump or truck and the procedure is pretty straight forward. Off airport usually implies that one is using fuel cans or a personal tank/pump combination. For fuel cans, most of the ones available in the local hardware store are made of "plastic" due to price considerations. Personally I do not like the "plastic" containers as very few of them are of the more expensive electrically conductive material and they can actually contribute to the creation of electrostatic charges ... not good around fuel. I much prefer the use of metal fuel cans and have bought several of the Briggs & Stratton WM521 steel Jerry cans. The one thing I don't like about these cans is the "plastic" extension on the V-spout that could actually create electrical isolation ... I still need to test the "plastic" extension to see if it's conductive.
Another option for personal use is to mount a transfer tank on a truck, a trailer or in the yard as appropriate. One can then use something like the electric Fill-Rite transfer pump to fuel the craft from the larger supply tank. If one is using a yard tank then they should probably check to see if there are any county ordinances that prohibit their use or limit their size. Underground tanks usually incur a lot more regulations and hassles. The one advantage of a truck or trailer mounted tank is that it can be taken to the wholesaler or airport for a fillup whereas a larger tank in the yard will require a fuel delivery service.
I started looking at the option of truck bed transfer tanks and there are a lot of options available, both in size and configuration (i.e. combination transfer tank and toolbox). However, as I did some more reading there was a subtle distinction that became more apparent: flammable vs. combustible fluids. It would appear that most of the transfer tanks are designed for fluids such as diesel and are not suitable for gasoline (mogas or avgas). Gasoline transfer tanks are available but they are usually more expensive ... one such manufacturer with a large installer network is Transfer Flow.
One of the big concerns with aircraft fuel is contamination (particle and water) and that's why we check the gascolator. When refueling from cans or drums, I've heard of lots of "tricks" that may help to reduce the transfer of any contaminants but some are dangerous and of dubious merit. For the small cost, I think it is best to get a special purpose funnel that has a filter, a proven water separator and is built from electrically conductive material. Such a device is available from Mr. Funnel.
The fuel cans or transfer tanks make it easy to refuel with 100LL when one is away from an airport. However, there is a potential problem when one only has small cans or tanks. While talking to the local FBO, they indicated that they are not allowed by law to put fuel in anything except aircraft tanks. Seems that there is an environmental concern that the leaded fuel could be used for something other than an aircraft. One needs to check with their fuel supplier before just assuming that 100LL will be available to be placed in cans or tanks.
Grounding During Fueling
Perhaps I'm a bit paranoid about the whole refueling issue, but I have personally seen the results of a gas station that had a fire ... not a pretty sight. I intend to always try to keep a fully grounded path between my fuel tanks, the refueling can/hose and earth. This is even more important right after a helicopter has landed as it tends to pick up an electrostatic charge during flight. Also, if one lands on a trailer then it is highly likely that there will not be a path to earth through the skids since there are the rubber tires in the path.
The filling of fuel cans requires the same considerations as when using them to fuel the craft. The cans should be grounded; ideally with a grounding wire but as a minimum just by placing them on bare earth. One thing to absolutely avoid is filling them while they're on a truck bed without the use of a grounding wire. Similar to when fueling an aircraft, the metal nozzle on the fuel hose should be kept in contact with the fuel can since any quality refueling hose should contain an internal drain wire.
Ironic: I recently watched an FBO truck refueling a composite aircraft and the driver was very careful to first run the ground wire from the truck to the metal on the main landing gear. However, this was a composite aircraft and the landing gear has absolutely no electrical path to earth, the engine, the fuel tanks or any other part of the plane ... it was a totally useless effort with a false sense of security. Sometimes you'll see the grounding clip attached to an exhaust stack and this would have worked since the engine was connected to the fuel tanks via a combination of braided and hard (i.e. metallic) fuel lines.
CLUTCH
The centrifugal clutch has a requirement to both slip during startup and to fully lock up at operating RPM. I am aware that most times the as-delivered system actually has too much drag resistance at startup and actually causes the blades to start turning immediately. The CHR solution to this is to spray some WD-40 onto the clutch drum lining so the shoes slip a bit more. I have talked to several owners who have done this and it appears to be quite effective. However, one has to be careful to not add too much WD-40 ... this will still allow lock up, but will require hand propping the blades to get initial engagement. One owner who had too much WD-40 on his clutch pads used brake cleaner to try get rid of some of it ... this worked but created a real mess.
I've become aware of another CHR personnel who only uses 100LL (in a well vented environment) to lubricate the clutch drum. The idea here is that the residual lead actually creates the slippage but I also have a concern whether the aromatics in 100LL will attack the adhesive used to bond the liner. Come to think of it, WD-40 can also be used to remove adhesive residue and I have a similar concern about it's useage. While all this is interesting, it would be much more prefereable if CHR (rather than the customer) would do some formal testing and come up with a single best approach to this. It would be even better if they chose to actually document their results and requirements such as this.
The lubrication treatment is a maintenance item that will need to be redone as required. The feedback I've received is that a bit more WD-40 is needed about every 50 hours.
After writing the above, it's interesting to note that I used an even different approach. A few drops of oil from the oil tank dipstick were allowed to run down between the gaps in the clutch shields. At first this didn't seem to make much of a difference other than to reduce the friction of the clutch when everything was stopped and still required hand propping to to get the blades started. There were quite a few starts due to balancing runs. After an overnight rest, on the next start the blades started turning exactly as one would expect (very slowly and smoothly after startup) and there was a smooth lockup.
I am aware of one owner who detected that three of the four springs that push the clutch shoes out were broken after about 200+ hours. This was noticed as a difference in the way the centrifugal clutch was engaging which led him to clean out all the WD-40 residue and inspect the shoes.
AIR FILTER
The Safari kit comes with a Brackett 6210 filter assembly and I assume most builders would use this assembly. The actual element has a 12 month or 200 hour or 50% covered replacement interval specification but ... it must be remembered that a helicopter often operates in a much dustier environment than a fixed wing aircraft. One hour of hovering over a grass or dirt field will expose the filter to a lot more contaminants than a fixed wing doing one taxi / takeoff / landing and taxi back on tarmac. Although it is somewhat difficult to inspect, the filter element should be inspected at much more frequent intervals than a fixed wing would do and the pilot should consider what kind of operations they have been doing. These filters are one consumable item that I think the owner should always have spares available rather than just purchasing them before a scheduled maintenance / annual event.
There are alternative elements available from companies like Challenger (CPE-1174) and Donaldson, but intially I'm planning on just using the Brackett 6205 filter elements (about $11 each from Aircraft Spruce). There is an excellent article here that provides some interesting insight into filter elements and how paper versus foam may react differently in the laboratory versus the real world.
TAIL ROTOR DRIVETRAIN
It would appear from the manufacturer's data that the life of
the tail rotor driveshaft pillow block bearings should not be an
issue i.e. they should go to a reasonable major overhaul interval
(i.e. 2,000 hours). However, this can be influenced by vibration
and exposure to contaminants. A rise in temperature is often used
to indicate a bearing that is starting to fail, or already has.
The temperature of the pillow blocks should be regularly checked
during shutdown or alternatively they could have Teletemps
installed on each of them to record their maximum temperature.
N.B. The pillow block bearings are actually of the "rubber"
support kind and in order to check their temperature it is
imperative to check the inner race ...
checking the housing does not yield any useful information.
The insert for the 3-jaw spider coupler just before the tail rotor gearbox gives me more reason for concern. If I read the specifications correctly, it is rated for ~10.9 HP (or 6.8% of engine HP) before derating it for shock loads. Various references commonly list that approximately 10% to 15% of engine HP goes to the tail rotor and other references quote 5% to 40% depending on flight regime, helicopter weight, etc. I'm not ready to work through all the math, but the Safari's coupler is certainly rated right at the very bottom of these numbers. CHR factory craft use a piece of hose and band clamps over this coupling as a dust cover and while it may slightly improve it's load carrying capability, it precludes easy inspection of the spider during a pre-flight.
This coupler should be carefully checked during a DI (Daily Inspection) for any slop in either end. I have an earlier model with only a single bolt on the input side and it started to oval and open up after only a few hours of running. Newer versions that have a key should not experience this. There is also a single setscrew on the output side and this should also be checked for any slippage.
The elastomeric Omega coupler off the rear of the main transmission does not give me as much concern as it appears to be rated for ~16 HP. However, this does not preclude the requirement to include this component in the pre-flight check. Note that since it contains an elastomeric element, it will tend to absorb and dissipate some of the engine's shock loads before they reach the spider coupler at the rear of the tail rotor driveshaft.
SPARK PLUGS
There are a lot of options available for spark plugs: cold, hot, massive, fine wire, etc. All of them are much more expensive than automotive plugs which makes one slow down when contemplating trying a new set of them. My engine came with a set of UREM-40E's and that is what I used initially. However, it appears that the engine was running very rich and I tried to track down the source. First problem was with the wiring of the LASAR® temperature probe which was easily fixed. I then started to do some more research into plugs.
The first thing that got my attention was that
Robinson uses REM-38E's on the R22's and that got me to thinking.
In a helicopter we run the engine at maximum RPM with high power
settings most of the time and it's important to monitor the CHT
gauge for overheating, especially during extended hovering
operations. Thus our engines probably run hotter than most
aircraft engines. It would seem reasonable to use a colder plug (like
the 38's rather than the 40's) in order to dissipate the heat
away from the plug and prevent problems like pre-ignition.
Sidenote: Hot plugs retain their heat longer whereas cold plugs
transfer the heat to the cylinder quicker and stay cooler.
Normally an engine that runs hot uses a cooler plug whereas an
engine that runs relatively cool uses a hotter plug to prevent
lead deposits and other gremlins.
I also talked to an experienced owner who had also gone through a plug change. His mechanic recommended using REM-37BY's which use a different nose design (projected gap) which puts the spark source much more in the open. The more I read about these plugs the more it appears there is a lot of merit in their design. There are a lot of reports of increased power and reduced deposits. The biggest disadvantage of them seems to be that they're not FAA approved for many installations and thus can't be installed. Since we're in the experimental category, I've installed a set and will give them a try.
CLEANING
One thing that becomes apparant after doing some testing is the need for cleaning. If one has used a good quality paint then most cleaners are quite effective on the cabin external areas and the boom. I tend to use isopropyl alcohol for a lot of cleanup tasks like this. The bubble is a different issue since one needs to be very careful of any chemicals that might effect the plexiglass. One product that I've used is Plexus which is available from many aviation suppliers. This worked extremely well at cleaning off bugs and other such grime.
Another area that one wants to check is the blades. We did some hovering tests in the fall and there were some mosquitoes around ... it's amazing how quickly their self-sacrifice makes a significant build up on the blades.
clean gascolator bowl and screen during first oil change to remove any fuel tank chips
Mags - http://www.undaerospace.com/cbt_files/virtualengine/Magneto/Virtual%20Engine.swf
Exhaust - lubricate ball joints with Mouse Milk at frequent intervals
DI
Trailering - loading
Annual
Bubble Maintenance
Cover - Bruce's Custom Covers
Grip bearings - ATF / bearing change
Fire extinguisher inspection: Return to manufacturer...if gross weight is below:
500 grams (17.6 oz.): RT A400
686 grams (24.2 oz.): RT A600
1420 grams (3.1 lbs.): RT A1200
Pulling rocker covers - sludge on exhaust indicates a burned guide or valve stem
Miscellaneous
Last updated: September 18, 2009