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Multi engine helicopters - Governor failure procedure

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Multi engine helicopters - Governor failure procedure

Old 3rd Jun 2021, 16:02
  #21 (permalink)  
 
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I wonder if the trend was trying to say something?
Hey young fella....you have to admit the Trend remained constant after the ground run....and did not get any worse did it?

Cheap hired help....pooh!

I bet your Management did not buy cheap unchangeable tickets and charge the Client for full fare tickets...and then pocket the difference....or use any air miles accrued by Staff Travel for their own personal upgrades!

The Owner was quoted by some as having said (no idea as to the truth of that statement)....."If my Chief Pilots will not steal from me....they will not steal for me!".
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Old 3rd Jun 2021, 17:30
  #22 (permalink)  
 
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I bet your Management did not buy cheap unchangeable tickets and charge the Client for full fare tickets
We didn't have a client SAS, we were employees of the oil company. Funny thing about staff travel, aviation advisor reported to the company that he saw no value in sim training, when pressed the company quibbled about the cost, company policy was that overseas travel was to be first class, we said that we would travel cattle class if cost was an issue, but the company declined the offer because that would have set a precedent to the perks that they, the managers, took full advantage of. In the wash the company relented to sim every two years for captains, co-pilots nothing. I must admit though it was extremely onerous travel, crossing the pacific dressed in pajamas and sleeping horizontal in a bed at 30 something thousand feet, we learnt what a tough life our managers had, our hearts bled for them for the privations they suffered.
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Old 3rd Jun 2021, 17:37
  #23 (permalink)  
 
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Originally Posted by megan View Post
.....The biggest fracas I ever saw was a pilot came back with an aircraft that failed the trend by a monumental margin, engineers decided a ground run was in order and during the check the engine self destructed big time....
Oh yeah, I remember that one well. I was the bunny who wrote the in-flight trend check numbers down that day (which was the SOP in that operation, outbound leg of first flight of the day the power trend check was done and recorded). When megan says failed the trend by a monumental margin, he's not exaggerating. The engine went from something like a +5 on trend the previous day to a -20 on that flight. Bunny hopped out on arrival back at base, engineer hopped in, started the hover power check. Kaboom. Engine exploded (an Allison 250-C30). From memory there was a video of all the excitement taken from the heliport tower showing the helicopter emerging from a cloud of blue smoke . What was left of that engine was written off.

Last edited by gulliBell; 4th Jun 2021 at 11:57.
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Old 4th Jun 2021, 11:15
  #24 (permalink)  
 
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I had a low side failure on the Sea King at sea about a thousand years ago.

Affected engine went to idle Ng and low Nf so it was easy to diagnose. Happily it was during the day and fine weather, so easy free deck landing. We burned some fuel off and practiced with the emergency throttle a bit then I had the FO fly for the landing as I “flew” the emergency throttle, keeping the affected engine about 20 percent Q behind the good engine. Just have to remember the Q goes down much quicker when the collective is lowered so you have to be brisk getting the Q down on the emergency throttle.

Had a FCU fail on the 412 too. We were practicing gov fail, rolled throttle down, checked idle numbers, etc with dual concurrence, flipped the gov switch to manual and the TOT went to 1000+ in about a second. Shut down and OEI approach back to pad. Visual insp, no damage to engine. FCU change. Only time I ever had a snag on the PT6. Well..except that time as an FO when it wouldn't start...until the tech came out and turned on the fuel switches....sigh. LOL
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Old 4th Jun 2021, 12:06
  #25 (permalink)  
 
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Originally Posted by Viper 7 View Post
.. We were practicing gov fail, rolled throttle down, checked idle numbers, etc with dual concurrence, flipped the gov switch to manual and the TOT went to 1000+ in about a second...
Cut and paste as follows:

We were practicing gov fail hydraulics on/off, rolled throttle down full open, checked idle numbers, etc with dual concurrence, flipped the gov switch to manual and the TOT went to 1000+ in about a second..
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Old 4th Jun 2021, 12:36
  #26 (permalink)  
 
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Not that has ever happened before....or get the wrong governor switch.....sometimes you see what you expect to see....and other Dummy confirms you both are.
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Old 4th Jun 2021, 12:54
  #27 (permalink)  
 
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Originally Posted by gulliBell View Post
Cut and paste as follows:

We were practicing gov fail hydraulics on/off, rolled throttle down full open, checked idle numbers, etc with dual concurrence, flipped the gov switch to manual and the TOT went to 1000+ in about a second..
Which is why Bristow moved the panel with the GOV switches to the other side of the centre console from the hydraulics panel. They also moved the TQ and Triple tacho gauges to the bottom right of the instrument panel - something weird to do with them being in the field of view during critical phases of flight, or something. Was entirely logical and based on experience, but made dealing with governor malfunctions in the (FSI) simulator interesting - couldn't find the damn gauges!
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Old 4th Jun 2021, 13:03
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Moving the triple Tach had more to do with the Bristow Mod designed in their mind to prevent Loss of RPM actions.....part of which was disabling the Torque Limiting system...which also removed the Torque Damping which made Torque Control really dodgy...and led to lots of overtorques and a mod to the mod for a system to record overtorques.....and ultimately the whole mess was shit canned and the aircraft returned to Factory Spec.....as I recall it.

The moving of the control panel was done by other operators as well....not just Bristow.

I do not know of another Operator who used any such Mod as the Bristow Torque thing.
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Old 4th Jun 2021, 13:43
  #29 (permalink)  
 
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Originally Posted by SASless View Post
Moving the triple Tach had more to do with the Bristow Mod designed in their mind to prevent Loss of RPM actions.....part of which was disabling the Torque Limiting system...which also removed the Torque Damping which made Torque Control really dodgy...and led to lots of overtorques and a mod to the mod for a system to record overtorques.....and ultimately the whole mess was shit canned and the aircraft returned to Factory Spec.....as I recall it.

The moving of the control panel was done by other operators as well....not just Bristow.

I do not know of another Operator who used any such Mod as the Bristow Torque thing.
I'm sure other operators will have moved the panel - it certainly made no sense ergonomically and the mistake described is very expensive!

The Bristow Tq modification was a direct result of a fatal accident in the North Sea, which MAY have been averted if the factory standard system had not been designed to limit Tq to 104% - saving the MGB vs the airframe is maybe not the best design compromise. The UK AAIB recommended that it be investigated whether the Tq limiting be increased, and a recording device installed to record any overtorques. The limiting was not removed, but "wound up". Governor instability was a natural result and a recognised issue. Later in service they installed the 'Hi Power mod' (TB-138/145) with an increased TO Tq limit, and a trim actuator for No 2 Nf, using a beep switch on the collective to help match Tqs as they became unstable.

AAIB report here: https://assets.publishing.service.go...982_G-BIJF.pdf
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Old 4th Jun 2021, 14:46
  #30 (permalink)  
 
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Reading the accident report reminds me of several things.....but lets focus on just one aspect of the crash.

The loss of rotor rpm figures in this.

212man explained the Bristow reaction and subsequent Mod to the 212 over concerns of rotor droop during an emergency.

So....212man......remind me of the Single Engine Procedures taught by Bristow and tested on Base Checks on the 212....where Pilots were taught to DROOP the Nr to gain maximum performance of the aircraft.....what was the Nr. number we used....was it 90 percent?

It was close to full up Collective .

That was for Engine Failure after TDP....with a continued Takeoff.

For those unfamiliar with Bristow's Base Check methods....the aircraft was always ballasted to approach something like 90-95% of Allowable Take Off Weight for that particular set of climatic conditions DA, etc.

That was for OEI but the Rotor doesn't know if there one or two engines driving it....it droops when there is not enough power being applied to the rotor to maintain the collective setting being applied.

There seems to be a contradiction there....droop it on one....and lets overtorue it on two but not droop it and accept the overtorques......no consistency in that

The other part of the Report that gets my attention....CFIT after Loss of Control after continuing to fly into IMC weather while trying to maintain surface contact visually.

That put the aircraft into an impossible position and it seems the AAIB and Bristow were looking for solutions for the wrong cause of the accident.

Last edited by SASless; 4th Jun 2021 at 19:48.
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Old 4th Jun 2021, 18:32
  #31 (permalink)  

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On the Puma course, early stages, we used to teach a simple “70/30” approach to a landing in the event of an engine malfunction (very rare on a Turmo engine due to no electronics, they had purely mechanical centrifugal engine governors). Having recovered the Nr and with the faulty engine secured, fly a relatively shallow, trimmed approach at 70 kts to a firm surface. At approx 100 feet agl flare the aircraft to about ten degrees nose up, aiming to touch down at about 30kts (translational lift burble point).

It saved a whole lot of faffing about with throttles. There’s no reason why it shouldn’t work on almost any helicopter...certainly I’ve used it twice on an A109 (engine chip light induced shutdowns with diversion to an airfield).
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Old 5th Jun 2021, 01:47
  #32 (permalink)  
 
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We had a chap caught out by the governor panel being positioned slightly different in the 212 and 412 centre console, one higher than the other. We operated both types, meant to grab the hydraulic and got the governor instead with predictable results. Not the first time some one has been caught out by aircraft having disparate set ups.

One interesting 212 failure by one operator was the practice of placing ones pencil on the centre console, chap lowered collective and an engine immediately went into manual. Pencil had vibrated out to be caught under the collective when it was lowered, edge of panel acted as a fulcrum, other end of pencil caught under the switch and lifted it out into manual.
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Old 5th Jun 2021, 07:22
  #33 (permalink)  
 
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Originally Posted by megan View Post
..One interesting 212 failure by one operator was the practice of placing ones pencil on the centre console..
I can imagine that exactly as described. It would never occur to me as being a possibility otherwise.
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Old 5th Jun 2021, 23:25
  #34 (permalink)  
 
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One interesting 212 failure by one operator was the practice of placing ones pencil on the centre console, chap lowered collective and an engine immediately went into manual. Pencil had vibrated out to be caught under the collective when it was lowered, edge of panel acted as a fulcrum, other end of pencil caught under the switch and lifted it out into manual.
In Vietnam in a Huey, a senior officer with nothing to do (cojo doing all the work) reaches over the console and selects GOV to MAN. With throttle full open, the aircraft leaps upwards, but being formation leader, the rest of the pack tries to follow him up. Then they have to rapidly reverse and try to follow him down, now that his turbine has burnt itself out and lost power. The Rubber Duck strikes again.

Senior officer claims he just picked up a clipboard to write something, and the string holding the pencil to the board must have caught the GOV switch. Yeah, not what the cojo saw.
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Old 6th Jun 2021, 04:59
  #35 (permalink)  
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Thanks for everyones input. Obviously, flight manual procedures come first. I was looking for general input to put a presentation together on the subject. Have even had the pleasure of a high side gov failure in a 355 a few years back. I wanted to put some power points together on the general differences between transitioning from single engine helicopters to twins. Lots of resources available online and in the books/manuals on Cat A procedures, engine failures etc but very little on governor/ecu failures. My own experience was confusing, and presented very similar to an engine failure on the good engine. I guess I am looking for some good cheats, on the diagnosis side of things. One you've figured out what you're dealing with, training takes over and it is usually manageable - but it can be hard to figure out in the heat of the moment, along with the surprise and a few screaming pax mixed in.. Appreciate the posts, all useful for what I am trying to do. Thanks
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Old 6th Jun 2021, 05:23
  #36 (permalink)  
 
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Originally Posted by Jelico View Post
...but it can be hard to figure out in the heat of the moment...
Modern digital engine controls will tell you which engine has the problem, not hard to figure out at all.
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Old 6th Jun 2021, 07:58
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I had a high-side governor failure on a BK117, at that time, the first one in Oz. None of us had flown twins, though we had thousands of hours in singles. The instructor was Japanese, and such things were never discussed.
I was in a high hover over trees when the alarm for a torque split sounded. Oh poo, can't hover, can't land, see if I can get some forward speed and fly away. Got to safety speed and climbing, look at the dials. One engine very low, one maintaining RRPM - but I didn't look closely enough at that dial, with adrenaline pounding and first ever apparent engine problem. Identify, verify, move roof-mounted throttle to idle.
Still flying. Hmm.. the "sick" engine is still running. Gently move throttle forward again, oops, high RRPM alarm. WTF?? OK, I am only 4 nm from the airport, fly it back, running landing on the grass, roll engines back to idle. All looks good. Advance "sick" engine - no problem. Advance "good" engine, RRPM go berserk again. Shut down.

A P2 line to the FCU failed, so the engine ran away high - safer than going low I suppose. But being alone in the front, I would have needed 2 hands on the throttles in the roof to manipulate the "good" back down to keep RRPM normal, and I needed one hand on the cyclic - no SAS, no autopilot, just raw inputs. No could do.

So, I learned something, and told the rest of the crews about it.
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Old 6th Jun 2021, 09:05
  #38 (permalink)  
 
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Originally Posted by Ascend Charlie View Post
...I would have needed 2 hands on the throttles in the roof to manipulate the "good" back down to keep RRPM normal...
And there is another advantage of modern digital engine controls, you don't need to touch the engine levers for this malfunction...hands can stay on the controls.
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Old 6th Jun 2021, 10:03
  #39 (permalink)  
 
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The modern machines can introduce a bit of a ‘gotcha.’
The 139 with a high side run up can give you an OEI warning against the good engine, only because it has wound itself down to try to compensate for the high side failure. NR is the key to avoid getting distracted by the OEI symbology, and as mentioned previously, a little up/down on the collective to see which engine responds.
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Old 7th Jun 2021, 04:24
  #40 (permalink)  
 
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High side failure at the worse time on a platform take off that resulted in ditching the 214ST. Lots and lots of lessons to be learnt.

https://www.atsb.gov.au/media/24790/199100020.pdf
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