Bell 412 ground spin

[rotorfla]

has anyone ever heard on a bell 412 or 212 spin to the left on the ground flat pitch no pedal max gross and dry ground spooling up engines, or has anyone ever heard of a 412 spin on the ground to the left at all.

[technoprat]

Yes, I've seen a 412 do it on start in Doha.
It was strongly suspected that there was a lot of pedal involved, but the pilot denied it.

[hillberg]

212/412 spin on start? never.

[fijdor]

Recall something like that on 212, aircraft was being readied and lightenned for VFR operation, autopilot has been removed. this happened on the flight test. Had to do with part of the AP still there or servos left in their last position. Aircraft almost ended up on it's side.

JD

[hueyracer]

It´s easy.....just advance the throttle on start-up as quickly as you can.....

(As seen done years ago by a student-happened so quickly that the instructor couldn´t react....)
Luckily, my A/C was parked away far enough.....

The 212 did a 90° turn on the dry ground (not max a/u w, of course), on engine shutdown..
After bringing it to idle and waiting for 2 minutes cooldown, the student turned the throttle in the wrong direction-at a blink of his eye....

NOT funny!

[RVDT]

Motoring YAW servo?

NEVER take your feet off the pedals in a Bell medium.

Know someone who had the habit of flying with feet off the pedals.

Pre-landing check - Force Trim off. (Feet off pedals)

Pedal motors to the stop! Direction of travel now visible through greenhouse window!

I think it has something to do with the way the servo is mounted vertically and if the input is not balanced.

Good check is FT OFF and running at 100% flat pitch. Feet near pedals to stop subsequent movement and tap each pedal direction (L/R) in turn to see if it motors on it's own. If it does just stop it with you feet and do not allow it keep moving of course. You may be surprised.

[212man]

So remind me how we do the accel/decl check then, without spinning? I don't believe the aircraft will spin from throttle alone.

[P6 Driver]

Back in the day when the AAC operated the Scout, it was common practice to stand on the skid and hang on during start-ups on ice to monitor the mighty Nimbus as the cab was powered up in case it span.

Slightly different from this type of spinning on start-up though!


Edited to add - it was the groundcrew standing on the skid, not the aircrew!

[hueyracer]

Guess you were not just opening the throttle within a second, hum?

[before landing check list]

It´s easy.....just advance the throttle on start-up as quickly as you can.....

The 212/412 would not spin left, it would tend to spin to the right.

[RVDT]

IDENTIFICATION
Regis#: 911FR Make/Model: B412 Description: BELL 412EP
Date: 04/02/2012 Time: 1144

Event Type: Incident Highest Injury: None Mid Air: N Missing: N
Damage: Unknown

LOCATION
City: OPA LOCKA State: FL Country: US

DESCRIPTION
N911FR BELL 412EP ROTORCRAFT WHILE TAXIING, TAIL ROTOR STRUCK THE GROUND,
OPA LOCKA, FL

INJURY DATA Total Fatal: 0
# Crew: 2 Fat: 0 Ser: 0 Min: 0 Unk:
# Pass: 2 Fat: 0 Ser: 0 Min: 0 Unk:
# Grnd: Fat: 0 Ser: 0 Min: 0 Unk:


OTHER DATA
Activity: Unknown Phase: Taxi Operation: OTHER


FAA FSDO: SOUTH FLORIDA, FL (SO19) Entry date: 04/05/2012

If the T/R struck the ground what does the rest of it look like?

[rotorfla]

faa report

That report is incorrect it was reported incorrectly aircraft never left the ground and tail is just fine.

[RVDT]

Well it is the FAA so...............................

[before landing check list]

....If it is the same accident right? We should not prematurely judge.

[Troglodita]

So remind me how we do the accel/decl check then, without spinning? I don't
believe the aircraft will spin from throttle alone

Spot on - I agree 100% 212 man and as BLCL says it would tend to spin to the right anyway.

Guess you were not just opening the throttle within a second, hum?

Hueyracer that is exactly what we do on accel/decel checks - idle to full throttle in less than 1 second then close throttle back to idle at 90% N1 - check it reached 90% N1 in 4 seconds or less

Trog

[hueyracer]

Your´re doing it one engine after each other, right?

[before landing check list]

Careful if the ground is a bit slick on the acceleration checks.

HR, yes one engine at a time.

[SuperF]

i fly the 204 not the 212, but strong wind from 7-8 o'clock would help to upset it, wouldnt it?

dry ground and mauw, i thought you would have to be unlucky to get it moving... although, smooth concrete?

[prehar]

It happened on a rig landing on a 212 , very light machine and strong winds from the left . After landing and throttle to idle produced a yaw to the left. The Safety guys would not believe us till it happened to a 412 later .The paint on the deck was badly scratched and the deck was warped and needed some denting / painting work .Probably the skid / deck contact was inadequate and lacked enough friction.
This is similar to what might happen on an icy surface too !!

[before landing check list]

When throttle was reduced to idle the demand for anti torque was greatly reduced (along with down collective of course) however the rpm was still high for a little bit (it takes a few seconds for RPMR to go to idle speed), that along with some left peddle in (not neutralizing it when reduction to idle) AND with a left crosswind AND slick deck (metal to metal) and it can spin. No mystery here.