Starting with the blades tied down.

[Steve76]

Hopped into the JR this morning and one of the "customers" announces that the last pilot tried to start the machine with the blades firmly secured to the tail.
Hmmm....

First I heard of it. Just as we are departing too...

Seems he didn't light it off but must have spooled up to somewhere between 10-20% N1.

The question is: When does 'starting with the blades tied down' come into effect in the Bell 206 series?

[Letsby Avenue]

Excellent question! All Jetbox pilots have either done this or are about to! (You can put me down as an almost)

[Gibbo]

Yep, those who have and those who will.

Part of the start checks I was taught was "blades at 90 degrees" (can't be tied down out there. You feel a dill when you do it, but it happens. :oh: )

I have seen a couple of light offs with blades tied down (its easier to stuff up at night) and the consensus at the time was that it probably doesn't hurt the aircaft.

[paco]

You are OK up to 25% N1 I believe

Phil

[sprocket]

:hmm: Most 206 pilots commit their first start of the day with the fuel switch in the off position anyway. I just thought that was their back up plan just in case the blades were still tied down. :)

[paco]

If you do that, the engine will quit halfway through the warm up!

Phil

[206 jock]

My instructor (aka Cov HEMS) told me that starting with the tie downs on was 'a bad thing'.

Checklist says if blades not turning by 25% N1, shut down immedaitely, as that means the blades are not free to move.

I guess if he didn't light off, you're ok.

But if you are so busy watching the TOT gauge and miss the 25%, I'd heard that it will wreck the whole drive train. I guess you'd call that a bad thing.....

[MD900 Explorer]

I heard a rumour of a guy over in Carp, Ontario (HTS) who has a few thousand hours and a few helicopters at his disposal, who went to start up a B3 and did'nt realise he had the blades tied down, until he tried to start it for the sixth time, and only then did he realise, as it was a mechanic who banged on the door and told him of the problem. :sad:

He got out of the JR and then ordered another out of the hangar, whilst the poor mechanics were wheeling the one he just f:mad: :mad: :mad: ed up, in. The mechanic apparently untied the blades for him on the new JR, as he was in to much of a rush to untie them himself. :{

I guess, when you have too much money and don't gve a ****, that is what happens. :ouch:

MD :ok:

[WASALOADIE]

What's the difference with stating with the blades tied and starting with the rotor brake on? Most military helo's use the rotor brake during start and it doesn't seem to have any adverse effects.

[212man]

Slightly more damaging is starting with the blades untied but the tie down still attached. A, now ex, 212 pilot did that a few years ago on an operation I was on. Didn't do the tail rotor and drive system much good! Happened at night doing a ground run, which just proves the point: treat every start as if you intend to go flying. Intake blanks is another good one.

[NickLappos]

The issue is that the engine is producing some torque during the start, and at idle, and the blade is restraining that torque thru its tiedown attach point on the blade.

when motoring prior to start, the air blowing thru the engine produces very little torque (the slow rotation of the rotor during a normal start is the give away, the torque the engine produces prior to lightoff is peanuts.) A semi-educated guess is no problem at all if the light-off does not occur. Proof? Think of the rotor rpm you get when motoring the starter. Now walk the rotor around with the tiedown in your hand at that speed. Are you harming the blades? I hope not, or else every rotor tiedown task is suspect!

If the rotor is tied down until after lightoff, the question is still "how much torque?" but the answer is more complex. The typical stalled torque of most engines is low, but the rotor blade was not designed to hold that torque. It is not the same as a rotor brake, which is attached to the transmission directly (usually thru the tail rotor drive). The rotor brake system is designed for that torque, the blade is not. I don't think most engines will harm most blades, but would I assure anyone that the aircraft is airworthy after such an event? Nope. call and ask the manufacturer, who will probably ask what was the indicated MP or torque during the event. A conservative person on the other end of the phone will probably ask you to inspect the rotor, blades and things for excessive lag forces (like a sudden stoppage inspection of sorts).

[212man]

I don't imagine the exhaust would do the blade much good either, depending on how long you were running for.

[SilsoeSid]

WASALOADIE;
"Most military helo's use the rotor brake during start and it doesn't seem to have any adverse effects."

Those that do, have a clutch that enables this to happen during normal operations.

Especially handy when dropping off troops in the vicinity of sloping ground, and when far from engineering backup with the possibility of a problem on start-up. (Sods Law!)

This practise has become the norm, especially since the incident in Split when the pax walked around the rear of the a/c into the tail rotor, despite the safety brief.


Hot pitot tubes and covers don't go together :uhoh:

[NickLappos]

SilsoeSid,

There is no clutch for most helos that are equipped with a rotor brake, the normal method is to simply lock the turbine with the rotor brake, and let the engine gas generator run, and the power turbine stand still. The engine produces some torque as the combustion air blows against the power turbine, but the brake is designed to handle it.

A few helos have a clutch affair, but this is to allow the engine to run a gearbox that drives accessories. The rotor brake is not part of those systems, usually.

[Oogle]

Heard a story about a chap in Oz starting a HEMS machine (BK117??) with the tail rotor tied down. It was only picked up by an observer when the aircraft landing at the scene --

"Hey mate, what's that thing on your tail rotor?"

A few red faces no doubt. :\ :O :ooh:

[IHL]

MD900 Explorer : I know of this guy , he then probably fired the engineer out of priciple and then sued him for damages.

[Steve76]

IHL: French Canadian per chance?:hmm:

[John Eacott]

The Sea King has a fairly substantial tail rotor flapping restrainer, which clamps around the root of the blades alternately pushing on one root, pulling on the next, and is screwed in place: akin to clamping the Forth Road Bridge on the tail ;)

The crew who actually went flying with one still in place, weren't at all fussed with the aft CG problem, nor the slight restriction in the yaw pedals. But they were a bit tardy arriving in the bar to pay their dues :cool:

Then there was the CFI who arrived at Essendon Airport in an Agusta A109A, which had had to be lifted by a crane when it landed (at another airport) and the starboard UC collapsed. On arrival at Essendon, he wasn't able to answer too quickly, when asked

"how did it fly with the lifting shackle still attached to the main rotor head?". Good pre flight, huh?

[MD900 Explorer]

IHL / Steve 76

You are both on the money, i don't know how you do it sometimes. how uncanny eh? :E

MD:ok: