Wind V shutdown ?

[Vfrpilotpb]

Here in the UK we have had recently some very big winds, with gusts far stronger than most pilots will have flown in, my question is, " You take of and fly to your destination, with an eye on the time and the Wx, <img border="0" title="" alt="[Eek!]" src="eek.gif" /> you then return to your final LZ, thing is the wind has got up during this last part of the flight, you start to land, and are able to cope with the wind, but the gusting is very severe, what do you do, how do you shut down without any danger of the blades sailing to extremity and possibly hitting your tail, for upon initial shutdown the rotor brakes really are not much use, would you tilt the disk slightly forward so as to give added clearence at the tail end, or could this create problems at the front? <img border="0" title="" alt="[Eek!]" src="eek.gif" />

[Devil 49]

Slight forward cyclic and a good rotor brake are your best bet, assuming open area. You want to minimise uncontrolled blade movement, i.e. the bouncing and banging stop-to-stop as it turns down. Moderate cyclic use after the engine will help, but at some point the rotor stops being a wing and goes random. One sweats bullets then. Aside from that... Avoid shutdowns on rooftop helipads (more below) and generally, in the lee of buildings. I say "generally" because if the structure is substantial enough that it blocks the wind sufficiently, I'd head for it's wind shadow as a first choice. The lee of a stand of trees helps too.. .ON the rooftop helipad option mentioned above, some considerations. If your flight is generally smooth and the the gusts are only obvious after landing, you could well improve your situation by landing at an elevated pad.

[paco]

Park with your nose slightly out of wind, so whatever disk there is doesn't go for the tailboom. .. .Pnil

[heedm]

We have a high wind shutdown procedure. Wind is at ten o'clock, nonessential crew depart aircraft, one engine shut down the other brought to ground idle. Bring the rotor down to rotor brake limits (collective if required), apply rotor brake. If it engages, shut down second engage. If it doesn't engage release rotor brake and use second engine to bring rotor back up to speed.. .. .Now you have to decide whether to shut down without a rotor brake, go somewhere else, or hot fuel until the winds go down.

[tecpilot]

Very interesting thread. Discussed the question several times in the last weeks due to big winds and gusts up to 50 kt. Initiated from a cutted fin on a BK 117, some jokes from maint. guys and ended in a sour FOM (on the controls during the fin shortening). High wind shutdown procedure depends on the wind and surface conditions and of course, the type of helo. Sometimes it`s not possible to avoid such conditions. Hey heedm, hot refueling and standby sounds good at night in a city between buildings or on a hospital! How long do you want to stay there? Just kidding On an rigid main rotor like BO 105 and BK 117, there is no risk of damaged rotorstops, mastpounding... Sounds easy and FM says, pilot be cool up to 50kt headwind/ 45 kt other directions. But also on this rigids we have uncontrolled blade movement and bending under gusty or turbulent wind and especially with vertical wind components. Why ? Aerodynamics! Stabilising centrifugal forces are much less than at full RRPM and extreme lift changes on the blades. Applying collective to decrease RRPM may end in a blade stall with abnormal flapping down. Above 70%-60% RRPM i believe it`s safe. On some helos it`s strictly prohibited according to FM. Same procedure with stick movements. Very strong MR reactions with decreasing RRPM. Also have some reports that stops on hinged rotors doesn`t help because of the very strong bending moments, blade tips going down. Not the alldays weather! Use the brake to decrease and fix the controls. On dual controls use caution to your sideman. Ten o`clock to two o`clock wind seems ok. A look from outside during shutting down to blade movements and distances thrills really.. . . . <small>[ 14 March 2002, 01:04: Message edited by: tecpilot ]</small>

[talkturn]

To summarise and back to basics for us 'basic helicopter' pilots. Shut down 30º out of wind (does'nt really matter which way). R22 R44 - Do not raise collective - may disengage the teeter head friction. Possible use of stick toward the wind to take pitch off the advancing side. Gentle use of left pedal to increase drag and slow things down.

[Helinut]

talkturn,. .. .I don't disagree with you in respect of R22/R44 (or probably most 2 blade MR helicopters) but this may well not apply to other types. For example, the Squirrel family AS350/355 has a higher rotor start/shutdown limit from ahead (50 kts) than any where else (40 kts).

[talkturn]

fair enough . .thanks. .I will have to think about why that is

[Aesir]

It makes sense to shutdown with the wind from about 1 or 2 o´clock position on CCW rotation helicopters. This will cause the upwind blade to lift over the tailboom as lift increases due to more relative wind and vice versa on the retreating blade. However landing with the wind at 3 o´clock position may be difficult and dangerous due to forces on the tail trying to push the A/C upwind!

I dont know why so many RFM for turbine helicopters have higher limits with the wind on the nose other than it maybe having to do with danger of higher temps during shutdown if wind is blowing into the exhaust?