Dirty blades
 

How often or at what stage of dirt deposits should TR and MR blades be cleaned ?- what is the best method of cleaning and with what solutions ? What kind of lift ' robbing ' occours with a significant dirt film ? Thanks Yaw'll !


TFS

Throughout the years I have just used plain warm soapy water and sponge! Does the job and saves you having to find out what chemicals and the like can't be used on your blades!

Mate told me he used Mr Sheen to finish off his blades after a wash and gets great performance from them. No doubt the other guys on here will provide other ideas for you. Got to watch what you use though, don't want your blades delaminating on you!

TiP:ugh:

In my experience dirt's effect is small, but those bug carcasses that create bumps make measurable difference in power and also in stall speed, and sand erosion is even worse.

I agree that soap and water, and a soft non-abrasive scrubber do the trick at the factory.

And don't forget to clean all the bird poop and bugs off before tracking and balancing :D Will make life alot easier.

Really makes a diiference when chemical and bugs have built up after spraying all morning, especailly on a calm wind day. Soap and water work great.

A good indication is if your windows need a clean, then so do your blades.

When flying in a desert environment quite a while ago now in
UH-1's, I had to land one day due to bad vibes which were caused by the accretion of very fine dust (kind of like talcum powder, almost, except it was red) that had built up and caked solid on the leading edges.
Had crew and a couple of pax on board, so we all took turns hoisting eachother up on shoulders and 'abrading' it off as best we could with rags and stuff.
Surprising how tenacious it was, and how much of a vibe built up quickly.

In extreme conditions salt on the rotorblades may have significant effect on performance. In one instance a rescue helicopter with a cruise speed of 110 kts could only be flown at 80 kts due to vibrations. This happened following hoist operations in a 80kts wind. In another case a helicopter in the North Sea was forced to reduce speed to the point where it was doubtful i would reach land. However, after flying through rain, inter-helmet temperture returned to normal.

Next time I wash mine I will try the polish trick..i'll let you know if there is any noticable difference:ok:

Micky - someone told me of some authority last night, never ever polish your blades. Just passing that on...:oh:

Mild soap and water works the best. Do not use any silicon based wax to polish the blades. According o Bell this will make repairing the blade very difficult. Tail rotor blades should be cleaned everyday so they can be inspected daily.

Polishing blades was pre-requisite prior to a C of A test flight. It certainly works, and will never hurt your blades. Keeping you blades washed and cleaned is a basic maintenance action, that no only keeps them clean, but ensures the blades are receiving a continuous detailed inspection. A dirty aircraft and dirty blades are indicative of inferior maintenance and inspection.

The only person I can imagine suggesting that would suggest that you never polish blades is some workshy shirker who would rather surf the Internet than actually do any work!:eek:

Blade polishing can be fraught with problems, as S92mech stated: have a look at the MM before contemplating, let alone starting, any blade polishing. A lot of manufacturers place restrictions on what can and can't be used on main rotor blades. I had a set of LongRanger blades polished with a proprietary teflon polish, but only after it went through an approval process: well worth it, it put 9kias on the cruise speed :D

The BK117 is very sensitive to dirty blades: if it ever feels rough, or in need of a track and balance, a good wash of the MRB's will very often smooth everything out again. A lot cheaper than a T&B, too :ok: We use CarbonX to clean the tail rotor blades on the 206's, very efficient and easy to apply, gets all the grime and soot off.

On second thoughts, warm water and a little fairy liquid seems good enough for me:ok:
You don't go that fast in an old shark anyway:rolleyes:

You want to be real careful with anything you wash baldes with. Make sure it is non caustic, even common "enviormentally frinedly" cleaning products like 409 or simple green can cause corrosion. The H500 PM specfically states do not use 409 or like cleaners. Alwys use a approved aircraft soap .

CarbonX is good stuff.

Carnauba wax works well , and can help in dry enviroments.

Always remember a clean heliocpter is a happy helicopter, though sometimes it is just not possible to wash in the field.

RB

Being a little controversial - A little dirt on the underside of Main blades actually increases the Coefficient of Lift by increasing the Drag on the lower surface - Therefore if you polish the upper surface and don’t polish the lower surface performance should be somewhat enhanced.

I haven’t tried this on helicopters but it worked very well on a fleet of Light Fixed-wing aircraft. However, Blades are much more sensitive than wings. So –

A Word of Warning - If you do this you won't know how much of a difference you are making to each Blade!

Personally, I would just stick to washing with mild soap and lots of water, at least as often as the AMM says, if not flying in ‘messy’ conditions. Try to finish off with a little WD40, or approved similar oil , on a cloth to give them a bit of water protection (and a nice shine too!).

Good hand washing also means you are having a good look at what condition your blades are in. You will notice; condition of any caulking between pockets; Paint flaking, Delamination, Dents, Holes, Corrosion, etc. and then be able to keep an eye on them.

We have four Bell 47's here and one in the UK. In our experience polishing the blades makes them rough until the polish wears off a bit. I think that unless the polish is exactly the same on each blade the blades don't seem to follow the same track. If they are not polished they fly fine. Another small point, I would not recommend using washing up liquid as they use salt as a wetting agent.

Regards,

Chopperpilot47

Rigga,

IMHO, WD40 is generally a PITA :rolleyes: It is a requirement on most Bell two blade systems, to give protection to the bonded area where the fingers are stuck together. Otherwise all it does is create a nice sticky area for dust to get on to, creating a dirty set of blades after one flight :(

Somewhere along the way the original requirement seems to have been hijacked, and WD40 seems to be used on all sorts of blades, quite unnecessarily in most cases.

Polish your way to safety
 

An AS355 failed it's height climb coming up to a 100hr. Blades surfaces quite eroded, and leading edges clean but pitted. Long discussion with Marignane and some serious elbow grease resulted in 1000' per minute improvement in rate of climb.... so if your power is marginal, I can only recommend the elbow grease option!

dirty blades
 

Polishing the upper surface of UH-1 blades is a recognised servicing by the OEM. We normally use a polish called MINMUM, but any car polish is OK. When we operated Sea Kings off a ship, we would regularly hose down the blades whilst the rotors were turning to get the salt off them. We would have massive vibes just from the particle build up on the leading edges.