No Collective, No Problem!

[BOATFIXERGUY]

OUTSTANDING JOB!!!

 

NTSB Identification: CEN10IA397

Nonscheduled 14 CFR Part 135: Air Taxi & Commuter

Incident occurred Monday, July 12, 2010 in Gulf of Mexico, LA

Aircraft: BELL 206, registration: N523RL

Injuries: 2 Uninjured.

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

 

On July 12, 2010 at approximately 1430 central daylight time, a Bell 206 L4 helicopter, N523RL, experienced a flight control malfunction over the Gulf of Mexico approximately 62 miles south of Patterson, Louisiana. The commercial pilot and one passenger, who were the only occupants, were not injured. The helicopter was owned and operated by Rotorcraft Leasing LLC, Broussard, Louisiana. Visual meteorological conditions (VMC) prevailed at the time of the incident and a company flight plan had been filed for the Title 14 Code of Federal Regulations Part 135 passenger flight. The helicopter was attempting to land at a production platform in Eugene Island block 208-K after departing another platform approximately one mile away.

 

While on final approach, the collective flight control became disconnected at the bell crank just below the collective arm on the transmission and the pilot executed a go-around. With no control of collective pitch, and with the power fixed at 45 percent torque, the pilot completed a "slow climb to 1,000 feet and 60 knots". The pilot flew the helicopter back to the Harry P. Williams Memorial Airport (PTN) Patterson, Louisiana and made a high speed run-on landing on a 5,400 foot long runway. The FAA inspectors that responded to the scene and examined the helicopter reported that maintenance to replace the transmission and main rotor hub had been completed within the past week.

 

The helicopter was moved to the operator’s hangar at the PTN airport for further examination.

[heli.pilot]

Wow... I wonder what he did once he touched the skids? How do you get weight on the skids to stop your ground slide? Kill the engine during the ground slide?

[PhotoFlyer]

I don't know what the pilot did, but you wouldn't need to do much. An L4 won't hover at 45%, so it's just a matter of letting it slow down on it's own. Rolling off a little throttle would help also. You just don't want to roll off to much, since you lose tail rotor authority as RPM slows.

 

He's lucky this happened when he had enough fuel to get back to the beach.

[ChprPlt]

Sounds like a good job by the pilot!

[Goldy]

Wow... I wonder what he did once he touched the skids? How do you get weight on the skids to stop your ground slide? Kill the engine during the ground slide?

 

I bet he slid a bit further than you do when training! Sounds like a great job done, the added drag will slow you down eventually.

 

Goldy

[clay]

Awesome job to the pilot! I used to limit control movements to my students, Or power settings to students to simulate different problems. Limiting someones take off power is a great way to teach finess. I still do it to myself coming off platforms or onto them. Set a power setting coming in and try to make the approach without changing the power setting. Same thing coming off. Sorry about the off topic. But just made me think about it

[Lindsey]

Okay, complete noob question here:

 

How would you perform this maneuver? Step-by-step. Maybe I'm just not thinking clearly, but how do you adjust engine RPM without a collective? Also, how would you deal with what PhotoFlyer mentioned about the possibility of losing tail-rotor authority?

 

Thanks, guys. Learnin' something new every day!

[Shaun]

OUTSTANDING JOB!!!

 

the collective flight control became disconnected at the bell crank just below the collective arm on the transmission

 

 

maintenance to replace the transmission and main rotor hub had been completed within the past week.

 

After the helicopter leaves the shop they sweep up and bam! Mystery bolt! oh well put it in the jar.

 

 

I flew a Decathlon once where if you did a loop you could hear this nut rolling around somewhere. Man I love aviation.

[lelebebbel]

Okay, complete noob question here:

 

How would you perform this maneuver? Step-by-step. Maybe I'm just not thinking clearly, but how do you adjust engine RPM without a collective? Also, how would you deal with what PhotoFlyer mentioned about the possibility of losing tail-rotor authority?

 

Thanks, guys. Learnin' something new every day!

 

Obviously we don't know what exactly this pilot did and what the details of his problem were, but in theory (and in the training environment) the maneuver is performed as follows.

 

Given:

- Helicopter is in forward flight

- power / pitch becomes "stuck" at a value that is less than required to hover, but enough to sustain level flight at a certain speed.

 

Altitude or climb- and descent-rate can now only be controlled by changing airspeed. At or near Vy, the helicopter might be climbing.

At speeds higher than Vy, it will start to descent.

If airspeed is reduced, the helicopter will initially climb, but once speed is reduced to ETL or somewhere close to that, it will slowly start to descent.

 

Depending on where the collective is stuck, one can now attempt a running landing by either...

 

1) using forward cyclic (and possibly, steep turns) to descent towards a long runway, and run the helicopter on at high speed, which is what apparently happened here.

 

or

2) reducing airspeed until the helicopter slowly settles to the ground, then use forward cyclic near the bottom to control the rate of descent and run on at low speed.

 

Either methods has advantages and disadvantages.

 

Once on the ground, reducing the throttle slowly will keep the machine from taking off again. The RPM decay is not sudden, so TR authority should not be a big issue.

I can only speak for pistons, but personally I wouldn't mess with the RPM too much until I'm on the ground unless I had no other choice.

 

 

For those wanting to try this in a training helicopter, don't do it without an instructor.

In the R22 (at sea level) I usually give my students a "stuck collective" at power settings between 18 and 22 inches.

Edited July 24, 2010 by lelebebbel