Helicopters R Us

[jdgretz]

Originally Posted by Shadow10

Can someone with knowledge of such things give us a bit more info on the condition the pilot described leading to the crash?

Sounds like a hydraulics hard over. Basically the valves on the hydraulics controls ceased functioning and jammed the controls. Sometimes recycling the on/off switch for the hydraulic control system will unstick the pump/valves but you do need a couple of seconds to do that. If that does not work, you can try pulling the circuit breaker and punching it back in. If neither of those work, you turn off the system, pull the circuit breaker and both pilots try to wrestle the system into some sort of flyable configuration. The Cobra has an emergency accumulator/hydraulic pump that can be turned on to provide hydraulic power for a very limited time. It is normally used only on final approach as you don't get much use out of it, so it is a last resort sort of thing.

Cobras also have a stability augmentation system that the old UH-1 does not have which also complicates matters. See http://www.liberatedmanuals.com/TM-1-1520-236-CL.pdf or TM 55-1520-236-10 page 322 for more information.

A simple hydraulics failure as opposed to the hard over is much easier to deal with. In the simple situation, the pump just quits pumping but everything else works - no closed valves, etc. Not a lot of fun, but flyable and pilots do train on those maneuvers.

I know many of the folks at the Army Aviation Heritage Foundation (flew with some of them as well back in they day) and all their pilots are very experienced and capable.

jdg

[GunshipDriver]

Reversals at low altitudes and low airspeeds are never a good idea imo. I know of other H-1s that have been planted by highly trained and capable pilots. It will be interesting to note how the AMB investigation goes in regards to what they do or don't find in their further examination of the mechanical system to include hydraulics and scas.

[Elvis70]

Sorry about the loss of your crew mate and friend.

[Vagabond_Explorer]

Originally Posted by jdgretz

Sounds like a hydraulics hard over. Basically the valves on the hydraulics controls ceased functioning and jammed the controls. Sometimes recycling the on/off switch for the hydraulic control system will unstick the pump/valves but you do need a couple of seconds to do that. If that does not work, you can try pulling the circuit breaker and punching it back in. If neither of those work, you turn off the system, pull the circuit breaker and both pilots try to wrestle the system into some sort of flyable configuration. The Cobra has an emergency accumulator/hydraulic pump that can be turned on to provide hydraulic power for a very limited time. It is normally used only on final approach as you don't get much use out of it, so it is a last resort sort of thing.

Cobras also have a stability augmentation system that the old UH-1 does not have which also complicates matters. See http://www.liberatedmanuals.com/TM-1-1520-236-CL.pdf or TM 55-1520-236-10 page 322 for more information.

A simple hydraulics failure as opposed to the hard over is much easier to deal with. In the simple situation, the pump just quits pumping but everything else works - no closed valves, etc. Not a lot of fun, but flyable and pilots do train on those maneuvers.

I know many of the folks at the Army Aviation Heritage Foundation (flew with some of them as well back in they day) and all their pilots are very experienced and capable.

jdg

I looked carefully at the video - it doesn't look like the pilot had a hydraulics failure. It looked like he was in perfect control of the attitude right until the crash. However, I am just speculating. To me, it looked like he misjudged the height - however I am willing to be corrected. jdgretyz - are you talking about recycling the SACS (at the bottom of the cyclic grip) rather the the actual hydraulic system? As you know, Cobras will fly without the SACS but there's less stability. Just wondering...

[fireflyr]

Originally Posted by GunshipDriver

Reversals at low altitudes and low airspeeds are never a good idea imo. I know of other H-1s that have been planted by highly trained and capable pilots. It will be interesting to note how the AMB investigation goes in regards to what they do or don't find in their further examination of the mechanical system to include hydraulics and scas.

I agree. I doubt they will find anything wrong with the hydraulic / flight control system. I had a irreversible valve failure in a 205A1++ while in a left turn and it tried to roll over on its back. The cyclic locked to the left (where it had been displaced for the turn) and I was only able to move it when the reservoir on the roof replenished the servo. I got the cyclic centered and then turned off the hydraulic switch and landed the aircraft in a field. I've had 4 complete hydraulic failures over the years and never crashed.

In my opinion, he just attempted the maneuver too close to the ground.

Disclaimer: We all know what opinions are worth.

[jdgretz]

Originally Posted by Vagabond_Explorer

I looked carefully at the video - it doesn't look like the pilot had a hydraulics failure. It looked like he was in perfect control of the attitude right until the crash. However, I am just speculating. To me, it looked like he misjudged the height - however I am willing to be corrected. jdgretyz - are you talking about recycling the SACS (at the bottom of the cyclic grip) rather the the actual hydraulic system? As you know, Cobras will fly without the SACS but there's less stability. Just wondering...

No, actually hitting the circuit breakers for the hydraulics control system. Sometimes recycling the power to the system will get the valves or pump working again.

The emergency procedures called out include:

• Emergency Hydraulic Pump Switch - OFF (pilot and gunner)
• Hydraulic Control Circuit Breaker - IN
• SCAS - Disengage appropriate Channel
  • System 1 - Yaw
  • System 2 - Roll and Pitch
• Emergency Hydraulic Pump Switch - On for final approach

The above is for a single channel failure. For a dual channel failure, you shut the whole system down using either the SCAS button or the SCAS Control Panel.


You should have circuit breakers for Hydraulic Control (main pump power), SCAS Power and Emergency Hydraulic Pump Power on the Essential Buss Circuit Breaker Panel as well as SCAS Power on the 115v.


If the standard emergency procedures don't work, recycling the main SCAS power will sometimes work. Given enough time, altitude and airspeed, you try them all. Hopefully something will knock some sense back into the hydraulic system.


Remember - punching the button on the cyclic will disengage the entire SCAS system which then needs to be re-engaged using the switches on the SCAS Control Panel.


I spent a bunch more hours in the UH-1 than the AH-1 and did my test pilot training in the UH-1 so my thinking runs that way first. Speaking of hydraulics rather than SCAS is a bit easier for someone who is not familiar with the peculiarities of the Cobra.


I too am curious to see what the tear down analysis of the hydraulic system show. Did he misjudge or did the hydraulics lock up? His initial statement to the board seems to indicate a failure of some sort.


jdg

[EvilGenius]

The new EC 175 just flew in to start off the US demo tour.



(Not my pic)

Quieter than I expected, short than I expected too.

[Vagabond_Explorer]

Originally Posted by EvilGenius

The new EC 175 just flew in to start off the US demo tour.

What is the interior like? Sometimes I feel like the cheapest Japanese cars have better quality than EC's interior. The AS350 has a plastic roof that caves in when the aircraft is parked outside in 100 deg F heat. The plastic that covers the pillar between the 2 windscreen perspex sags till it hits the instrument panel when exposed to direct sunlight.

The new energy absorbing seats are more uncomfortable than a wooden bar stool in a cheap hotel in Bangkok. At the hint of the smallest amount of rain, the windscreens or roof perspex or windows or chin bubbles lets water in.

They are fantastic powerful machines. If only Bell did the maintenance and any Jap car companies did the interior.

Just some personal experiences on EC's 350's, 120's, 135's, 130's, 355's, 145's, 117's. etc.

[EvilGenius]

Originally Posted by Vagabond_Explorer

What is the interior like? Sometimes I feel like the cheapest Japanese cars have better quality than EC's interior. The AS350 has a plastic roof that caves in when the aircraft is parked outside in 100 deg F heat. The plastic that covers the pillar between the 2 windscreen perspex sags till it hits the instrument panel when exposed to direct sunlight.

The new energy absorbing seats are more uncomfortable than a wooden bar stool in a cheap hotel in Bangkok. At the hint of the smallest amount of rain, the windscreens or roof perspex or windows or chin bubbles lets water in.

They are fantastic powerful machines. If only Bell did the maintenance and any Jap car companies did the interior.

Just some personal experiences on EC's 350's, 120's, 135's, 130's, 355's, 145's, 117's. etc.

I couldn't get close enough to see inside so I couldn't tell ya. Since it's a demo craft I wouldn't be surprised if it was really nice. We do have the capability of putting in really nice seats and interiors, but those are pricey and not much of a concern for most customers I do know what you mean by the regular seats though.

Dunno what to tell you about the drooping panels. I noticed they're a little thin when I used to prep them for shipping, but some genius though it was a good idea to face our hangar south and during the summer where it routinely hits 100+ for months during that time and I haven't heard of those issues.

I agree about the maintenance. I love disecting tech pubs that are written in two different countries whose languages I don't speak and have almost totally opposite ideologies about how to setup manuals and what constitutes relevant information.

[GunshipDriver]

you can take this with a grain of salt.. but reversals at 100' AGL are plenty doable.. but I would reccomend starting with 100-120 KIAS and executing a health pop when trading the airspeed (kinetic engergy) for altitude (potential energy) and then back on the descent when speeding back up. the one caveat I would mention though is being keenly aware of any strange crosswinds or the such which could make for a slightly uncomfortable situation as anytime you are closer to the ground there is that much less room for error.

[jdgretz]

Originally Posted by GunshipDriver

you can take this with a grain of salt.. but reversals at 100' AGL are plenty doable.. but I would reccomend starting with 100-120 KIAS and executing a health pop when trading the airspeed (kinetic engergy) for altitude (potential energy) and then back on the descent when speeding back up. the one caveat I would mention though is being keenly aware of any strange crosswinds or the such which could make for a slightly uncomfortable situation as anytime you are closer to the ground there is that much less room for error.

Of course they are doable - and relatively safely - considering you're in the red area for autos most of the time. Hell, the number of them performed in Nam without incident is testament to that.

As you say, you just have to be really aware of everything.

jdg

[AerialCameras]

[fz6kd7]

Originally Posted by AerialCameras

Did you do any filming on the vegas strip of this one?

I seen a red white and blue one and looked like it was being
Followed by another copter looked like filming etc.. anyway it looked
Nice

[AerialCameras]

Originally Posted by fz6kd7

Did you do any filming on the vegas strip of this one?

I seen a red white and blue one and looked like it was being
Followed by another copter looked like filming etc.. anyway it looked
Nice

Yep

[fz6kd7]

I forget what day but i seen it low and south of downtown
At sunset

I think you qualify for the cool job award