AS350 Start Procedure - Hydraulic Test
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AS350 Start Procedure - Hydraulic Test
We have just upgraded two BAs to B2s and the new RFM comes with direction to do the HYD TEST at 100% Ng.
I thought that it was industry best practice to do this at 70% Ng.
Does anyone have any guidance - official or otherwise on this?
I have searched the threads but I couldn't find anything that comes close to discussing this.
I thought that it was industry best practice to do this at 70% Ng.
Does anyone have any guidance - official or otherwise on this?
I have searched the threads but I couldn't find anything that comes close to discussing this.
Surely Nr?
I think generally the RFM takes precedence over "industry best practice" - call me old fashioned!
I think generally the RFM takes precedence over "industry best practice" - call me old fashioned!
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A rather disappointing response so far.
To rephrase the question
Are there any B2 operators who are doing their HYD TEST at 70% Ng rather than the 100% as stated in the RFM?
To rephrase the question
Are there any B2 operators who are doing their HYD TEST at 70% Ng rather than the 100% as stated in the RFM?
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I'm not sure the RFM says 100%ng. What the RFM normal procedures does suggest by sequence is that you would have already checked that the FCL was in the 'flight' position before you complete the hydraulic accumulator test. I'm not trying to be clever by any stretch, but being in the 'flight' position doesn't correlate to 100%ng.
I've always accelerated to flight after start and completed those checks at that time, on the assumption that the 'flight' position offers the best conditions for the check. In addition, I can then be sure that I am not hanging around in mid NR particularly 300-320 or worrying about what the wind is or isn't doing. There is something to be said for a thinking pilot vs a flying pilot but generally I think the French thought things through when they were writing the RFM and the DGAC was certifying it.
Check : fuel flow control in 'flight" position.
NOTE : During engine acceleration, do not allow NR value to remain steady between 300 and 320 r.p.m.
- Disconnect external power, if used
. Check : Warning-Caution-Advisory Panel GEN and BAT (4) lights off
- Switch on PITOT heating * .............. On pedestal panel (17)
Switch on the HORN
Check that the PITOT and HORN lights go out ............ (4)
Check All warning and caution lights oft ........................(4)
Electrical system voltage and current ............................(1)
. Engine oil pressure
- Run each booster pump separately and check that :
The fuel pressure is correct ........................... (1)
The FUEL P. warning light is on .......................(4)
- Switch on/engage all necessary systems (VHF, lights, windshield wiper*, etc)
NOTE : Do not use the wiper on a dry windshield or in light rain.
- Carry out a hydraulic accumulator test :
I've always accelerated to flight after start and completed those checks at that time, on the assumption that the 'flight' position offers the best conditions for the check. In addition, I can then be sure that I am not hanging around in mid NR particularly 300-320 or worrying about what the wind is or isn't doing. There is something to be said for a thinking pilot vs a flying pilot but generally I think the French thought things through when they were writing the RFM and the DGAC was certifying it.
Check : fuel flow control in 'flight" position.
NOTE : During engine acceleration, do not allow NR value to remain steady between 300 and 320 r.p.m.
- Disconnect external power, if used
. Check : Warning-Caution-Advisory Panel GEN and BAT (4) lights off
- Switch on PITOT heating * .............. On pedestal panel (17)
Switch on the HORN
Check that the PITOT and HORN lights go out ............ (4)
Check All warning and caution lights oft ........................(4)
Electrical system voltage and current ............................(1)
. Engine oil pressure
- Run each booster pump separately and check that :
The fuel pressure is correct ........................... (1)
The FUEL P. warning light is on .......................(4)
- Switch on/engage all necessary systems (VHF, lights, windshield wiper*, etc)
NOTE : Do not use the wiper on a dry windshield or in light rain.
- Carry out a hydraulic accumulator test :
Just make sure you lock the collective lever in place....
I was about 100 feet away and watched this one go down:
Safari Helicopters Hydraulic Check crash
LAX01LA083
On February 1, 2001, at 0918 Hawaiian standard time, a Eurocopter AS-350-B2 single engine helicopter, N985SA, impacted terrain and rolled over after an unintentional liftoff during a before takeoff check at Lihue, Hawaii. The helicopter sustained substantial damage; however, the pilot, who was the sole occupant, received only minor injuries. The helicopter was registered to and operated by Safari Helicopters Inc., of Lihue, as an on-demand, sightseeing, air-taxi flight under 14 CFR Part 135. The pilot was performing a before takeoff run-up on the Lihue Airport helipad, in preparation for flight's boarding and departure, when the accident occurred. Visual meteorological conditions prevailed at the time of the accident and a company visual flight rules flight plan was filed.
According to the pilot, he was in the process of conducting the hydraulic accumulator test during the before takeoff checklist when the accident occurred. According to the Eurocopter training manual, the helicopter can be maneuvered without hydraulic assists, "but this requires the pilot to apply non-negligible forces that are difficult to gauge." The training manual also states, "in case of loss of hydraulic pressure, accumulators in the main rotor servo actuators provide a small energy reserve, giving the pilot time to reconfigure in the safety configuration.
The helicopter's before takeoff checklist calls for a hydraulic accumulator test to be accomplished with the fuel flow control in the "flight" power setting. The test dictates that the collective pitch be locked down prior to testing the accumulators. The pilot is then instructed to cut off hydraulic pressure by actuating the hydraulic test push-button (located on the center consol). The hydraulic warning light will illuminate and the hydraulic warning horn will sound. The pilot is then instructed to "move the cyclic 2 or 3 times along both axes separately on 10 percent of total travel, check for hydraulic assistance by absence of control load." Once this is accomplished, the pilot is to press the hydraulic test pushbutton (on the center console) to restore hydraulic pressure.
At the time of the accident, the pilot was seated in the left cockpit seat. From the left seat, the collective is positioned to the left of the seat, the cyclic is centered in front of the seat between the pilot's legs, and the hydraulic test pushbutton is to the right of the seat on the center console. During the hydraulic accumulator test, while positioned in the left seat, the pilot has to remove his left hand from the collective control and place it on the cyclic control, then he has to remove his right hand from the cyclic and depress the hydraulic test pushbutton. The pilot then repositions his hands to their normal position (left hand on collective and right hand on cyclic). Once the test is complete, the pilot has to remove his left hand again from the collective and place it on the cyclic and remove his right hand from the cyclic and depress the pushbutton to restore hydraulic pressure.
According to the pilot, it was when he repositioned his hands to restore hydraulic pressure when the helicopter became airborne in a nose low attitude. The pilot quickly repositioned his left hand to the collective and his right hand to the cyclic. He attempted to pull aft on the cyclic, turn the aircraft into wind, and takeoff in order to gain a controllable airspeed. The aircraft immediately pulled back to the right and entered a back and forth oscillation. The aircraft "entered a figure '8' type of oscillation with a nose high then nose low position in extreme almost wing over attitudes." The helicopter descended like a "falling leaf" and struck the ground tail rotor first on the right side. The pilot heard a series of grinding sounds and observed the main rotor blades disintegrate upon ground impact. The helicopter came to rest on the right side, and the pilot shutdown the engine and exited the helicopter.
There are two types of collective locks utilized in the AS-350-BA and B2 helicopters. One lock (located on right seat collective) incorporated a steel plate, which slides over a stud mounted on the forward side of the collective head. The other lock (located on the bottom side of the left seat collective) utilizes a clip that is attached to and hangs below the collective arm, curving up at the end forming a c-shaped clip. The c-shaped clip wraps around a pin, which is mounted on the cockpit floor oriented along the longitudinal axis of the helicopter. The left seat collective lock utilizes a locking plate, which the pilot depresses while he pushes the collective lever down. When the locking plate is depressed, the clip is aligned with the locking pin and the clip automatically engages around the pin when the collective is lowered. When the locking plate is not depressed, the clip is offset from the pin preventing it from unintentionally engaging in flight.
The employment of either lock depends on an upward spring load incorporated in the collective control handle. In either case, the spring loading must be physically overcome in order to apply the locks, as well as to ensure that the control handle remains in the full down or flat pitch position. When physical pressure on the collective is released, the spring loading helps keep both locks in the locked position, while preventing the upward movement of the control handle.
Federal Aviation Administration (FAA) inspectors from the Honolulu Flight Standards District Office responded to the accident site, and, as part of the investigation, performed the hydraulic system check in a company helicopter identical to the accident helicopter. The inspector noted that once the hydraulic system check is performed and the pressure is bled from the accumulators, the airframe experiences transient 1:1 vibratory loads. This loading excites the collective control, and it reacts by bouncing up and down against the lock. The lock sometimes reacts by releasing the collective. The positive spring loading causes the collective, upon release, to suddenly pop up, putting some degree of pitch in the main rotor blades. This scenario was played out by the FAA inspectors and it was noted that feedback from the cyclic motion with hydraulic pressure off, coupled with the collective lock design, would result in the collective lock releasing the collective. In the accident sequence, the pilot's hands were transitioning and were not in position to offset the instantaneous and unexpected positive collective load.
According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot had accumulated a total of 14,438 flight hours, of which 7,632 hours were in the same make and model as the accident helicopter.
I was about 100 feet away and watched this one go down:
Safari Helicopters Hydraulic Check crash
LAX01LA083
On February 1, 2001, at 0918 Hawaiian standard time, a Eurocopter AS-350-B2 single engine helicopter, N985SA, impacted terrain and rolled over after an unintentional liftoff during a before takeoff check at Lihue, Hawaii. The helicopter sustained substantial damage; however, the pilot, who was the sole occupant, received only minor injuries. The helicopter was registered to and operated by Safari Helicopters Inc., of Lihue, as an on-demand, sightseeing, air-taxi flight under 14 CFR Part 135. The pilot was performing a before takeoff run-up on the Lihue Airport helipad, in preparation for flight's boarding and departure, when the accident occurred. Visual meteorological conditions prevailed at the time of the accident and a company visual flight rules flight plan was filed.
According to the pilot, he was in the process of conducting the hydraulic accumulator test during the before takeoff checklist when the accident occurred. According to the Eurocopter training manual, the helicopter can be maneuvered without hydraulic assists, "but this requires the pilot to apply non-negligible forces that are difficult to gauge." The training manual also states, "in case of loss of hydraulic pressure, accumulators in the main rotor servo actuators provide a small energy reserve, giving the pilot time to reconfigure in the safety configuration.
The helicopter's before takeoff checklist calls for a hydraulic accumulator test to be accomplished with the fuel flow control in the "flight" power setting. The test dictates that the collective pitch be locked down prior to testing the accumulators. The pilot is then instructed to cut off hydraulic pressure by actuating the hydraulic test push-button (located on the center consol). The hydraulic warning light will illuminate and the hydraulic warning horn will sound. The pilot is then instructed to "move the cyclic 2 or 3 times along both axes separately on 10 percent of total travel, check for hydraulic assistance by absence of control load." Once this is accomplished, the pilot is to press the hydraulic test pushbutton (on the center console) to restore hydraulic pressure.
At the time of the accident, the pilot was seated in the left cockpit seat. From the left seat, the collective is positioned to the left of the seat, the cyclic is centered in front of the seat between the pilot's legs, and the hydraulic test pushbutton is to the right of the seat on the center console. During the hydraulic accumulator test, while positioned in the left seat, the pilot has to remove his left hand from the collective control and place it on the cyclic control, then he has to remove his right hand from the cyclic and depress the hydraulic test pushbutton. The pilot then repositions his hands to their normal position (left hand on collective and right hand on cyclic). Once the test is complete, the pilot has to remove his left hand again from the collective and place it on the cyclic and remove his right hand from the cyclic and depress the pushbutton to restore hydraulic pressure.
According to the pilot, it was when he repositioned his hands to restore hydraulic pressure when the helicopter became airborne in a nose low attitude. The pilot quickly repositioned his left hand to the collective and his right hand to the cyclic. He attempted to pull aft on the cyclic, turn the aircraft into wind, and takeoff in order to gain a controllable airspeed. The aircraft immediately pulled back to the right and entered a back and forth oscillation. The aircraft "entered a figure '8' type of oscillation with a nose high then nose low position in extreme almost wing over attitudes." The helicopter descended like a "falling leaf" and struck the ground tail rotor first on the right side. The pilot heard a series of grinding sounds and observed the main rotor blades disintegrate upon ground impact. The helicopter came to rest on the right side, and the pilot shutdown the engine and exited the helicopter.
There are two types of collective locks utilized in the AS-350-BA and B2 helicopters. One lock (located on right seat collective) incorporated a steel plate, which slides over a stud mounted on the forward side of the collective head. The other lock (located on the bottom side of the left seat collective) utilizes a clip that is attached to and hangs below the collective arm, curving up at the end forming a c-shaped clip. The c-shaped clip wraps around a pin, which is mounted on the cockpit floor oriented along the longitudinal axis of the helicopter. The left seat collective lock utilizes a locking plate, which the pilot depresses while he pushes the collective lever down. When the locking plate is depressed, the clip is aligned with the locking pin and the clip automatically engages around the pin when the collective is lowered. When the locking plate is not depressed, the clip is offset from the pin preventing it from unintentionally engaging in flight.
The employment of either lock depends on an upward spring load incorporated in the collective control handle. In either case, the spring loading must be physically overcome in order to apply the locks, as well as to ensure that the control handle remains in the full down or flat pitch position. When physical pressure on the collective is released, the spring loading helps keep both locks in the locked position, while preventing the upward movement of the control handle.
Federal Aviation Administration (FAA) inspectors from the Honolulu Flight Standards District Office responded to the accident site, and, as part of the investigation, performed the hydraulic system check in a company helicopter identical to the accident helicopter. The inspector noted that once the hydraulic system check is performed and the pressure is bled from the accumulators, the airframe experiences transient 1:1 vibratory loads. This loading excites the collective control, and it reacts by bouncing up and down against the lock. The lock sometimes reacts by releasing the collective. The positive spring loading causes the collective, upon release, to suddenly pop up, putting some degree of pitch in the main rotor blades. This scenario was played out by the FAA inspectors and it was noted that feedback from the cyclic motion with hydraulic pressure off, coupled with the collective lock design, would result in the collective lock releasing the collective. In the accident sequence, the pilot's hands were transitioning and were not in position to offset the instantaneous and unexpected positive collective load.
According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot had accumulated a total of 14,438 flight hours, of which 7,632 hours were in the same make and model as the accident helicopter.
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And this illustrates exactly what the issue is...
If you carry out the HYD TEST at "Flight Position" and the collective lock is not engaged or is not effective, and there is a hyd malfunction, you will most likely end up on your side.
This was addressed I believe in the BA revised start procedures (HYD TEST at 70% Ng) But the B2 normal checklist still has the HYD TEST at Flight Position.
I would challenge that statement anytime! Servo Transparency anyone?
If you carry out the HYD TEST at "Flight Position" and the collective lock is not engaged or is not effective, and there is a hyd malfunction, you will most likely end up on your side.
This was addressed I believe in the BA revised start procedures (HYD TEST at 70% Ng) But the B2 normal checklist still has the HYD TEST at Flight Position.
I think the French thought things through when they were writing the RFM and the DGAC was certifying it.
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Generally if a pilot forgets to do something or something is broken on a helicopter, bad things happen.
Not having the collective lock on, or not guarding the collective can clearly have undesired consequences as pointed out by Gordy (always hard to look at those pictures), and yes no one gets everything right every time - ref Eurocopter or any of them. I still do believe that they try to at least get it right, and until otherwise instructed by the manufacturer or a regulatory authority, following the RFM is the industry best and safest practice.
I talked to a couple other 350 pilots and they indicated a test at full flight position is their sop. I also looked through RFM's for the B, BA and B3 but couldn't find any other procedure (revisions might not be current though).
Best advice - guard the collective (lock and hand), follow the RFM.
Not having the collective lock on, or not guarding the collective can clearly have undesired consequences as pointed out by Gordy (always hard to look at those pictures), and yes no one gets everything right every time - ref Eurocopter or any of them. I still do believe that they try to at least get it right, and until otherwise instructed by the manufacturer or a regulatory authority, following the RFM is the industry best and safest practice.
I talked to a couple other 350 pilots and they indicated a test at full flight position is their sop. I also looked through RFM's for the B, BA and B3 but couldn't find any other procedure (revisions might not be current though).
Best advice - guard the collective (lock and hand), follow the RFM.
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I was taught to do both the accumulator test and isolation test at ground idle before I knew anything about squirrels.
Our company has both B2 and Super D single engine variants. The pre take off checks in the company SOPs for both aircraft have both tests being carried out BEFORE advancing the FFL to flight idle.
Think about what the tests are proving... the accumulator test is simply proving that the accumulators will discharge within the few seconds that they should and that this discharge should be fairly uniform across all 3 of them. The isolation test simply proves that the hydraulics can be cut off in case of a hydraulics failure so as they don't come back unexpectedly and bite you on the arse as you run on.
Both checks can be proven whether at ground idle or flight idle.
Not making sure the collective is locked when it should be? That's a Darwinian issue methinks.
GP
Our company has both B2 and Super D single engine variants. The pre take off checks in the company SOPs for both aircraft have both tests being carried out BEFORE advancing the FFL to flight idle.
Think about what the tests are proving... the accumulator test is simply proving that the accumulators will discharge within the few seconds that they should and that this discharge should be fairly uniform across all 3 of them. The isolation test simply proves that the hydraulics can be cut off in case of a hydraulics failure so as they don't come back unexpectedly and bite you on the arse as you run on.
Both checks can be proven whether at ground idle or flight idle.
Not making sure the collective is locked when it should be? That's a Darwinian issue methinks.
GP
Last edited by Gas Producer; 5th Mar 2010 at 07:25.
It's been a while since I flew Squirrels but from memory part of the aim of the test is to check that the horn will come on to warn of a loss of hyd pressure when you select "test". If you perform the hyd test at idle you will not be able to test this part of the system. Furthermore, after you select the isolate switch the horn is re-set to prove that it has now been isolated from the hyd system and will now be available to operate in the event of low NR.
Mark Six
You are correct---It has a been a few years since I was current on Astars, but I do remember doing the test with the FFCL in the flight gate. After the accident I noted above, the collective guard was changed. I was working for a different company in Hawaii at the time and all aircraft had the guard changed.
You are correct---It has a been a few years since I was current on Astars, but I do remember doing the test with the FFCL in the flight gate. After the accident I noted above, the collective guard was changed. I was working for a different company in Hawaii at the time and all aircraft had the guard changed.
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Currently on a B2 moving drills, if the pad is snow or ice covered, like more often than not this time of year, I always do the test at 70% first to make sure nothing untoward is going to happen, ie spin or slide off the pad before I advance fuel control to the flight gate. If it is all good I then perform the check at 100%. And I always double check collective lock before I hit the teat switch. Bit off thread but I also know of a company here in Canada a few years ago doing annual PPC;s. While doing autos when the pole was dropped it somehow managed to engage the lock. Boys didn;t realise until time to pull at bottom of auto, resulting in hard landing and tail boom laying on ground, luckily no casualties......
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B2 hyd test
The flight manual says to do it at flight idle.I dont see how you could ever test it at 100 ng???i think you mean at 100% rrpm.If you do it at ground idle, hyd pressure will not be at it its maximum pressure.
As in the picture the same thing happened to a western operator in Canada when doing the hyd test a few years back.
As in the picture the same thing happened to a western operator in Canada when doing the hyd test a few years back.
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Siesmic boy
I should of clarified, 100% was a term loosely used to mean rotor rpm etc, not N1, if I had an N1 reading at 100% on the ground with no pitch pulled maybe wouldn't bother to do hyd test cos i think I would be shutting her down.
My engineer and I are currently sat in a exploration camp kinda bored so we just pulled RFM out of aircraft, LTS 101 super B2 and no where does it say to be done at 70% (flight idle), from what we interpret if you follow start up in normal proceedures, #4 para 3 it leads one to beleive full throttle (100%0 for test. Like I said in my previous post, I do it at 70% N1 and in the flight gate, so I guess my bases are covered, you from BC so ya know how pads are here, would hate to slide or spin off one
I should of clarified, 100% was a term loosely used to mean rotor rpm etc, not N1, if I had an N1 reading at 100% on the ground with no pitch pulled maybe wouldn't bother to do hyd test cos i think I would be shutting her down.
My engineer and I are currently sat in a exploration camp kinda bored so we just pulled RFM out of aircraft, LTS 101 super B2 and no where does it say to be done at 70% (flight idle), from what we interpret if you follow start up in normal proceedures, #4 para 3 it leads one to beleive full throttle (100%0 for test. Like I said in my previous post, I do it at 70% N1 and in the flight gate, so I guess my bases are covered, you from BC so ya know how pads are here, would hate to slide or spin off one
I had one get airborne during the hydraulic test once, I'm sure it was at full RPM as per the checklist - I must have inadvertently put too much downward pressure on the collective so that the flat steel type lock jumped off the stud and next thing I was in the hover wrestling it around over the pad.
I'm pretty sure from memory I hit the test switch again and then landed normally, with heart rate up quite a bit (this was in a B or BA, can't remember which).
You can hover them hydraulics off with difficulty but it's not something you'd want to do if you could avoid it, particularly if you're not into wind.
I'm pretty sure from memory I hit the test switch again and then landed normally, with heart rate up quite a bit (this was in a B or BA, can't remember which).
You can hover them hydraulics off with difficulty but it's not something you'd want to do if you could avoid it, particularly if you're not into wind.
Tis when one finds out that adrenaline is really brown
I did a quick check of the flight manual revisions for the following AS-350 versions: BB, D, B1, B2 and B3. All of these accomplish the hydraulic accumulator and pressure isolation checks at ground idle. I believe they all incorporate a note advising to accomplish these checks at 100% RPMR under windy conditions. It might be time to check your RFM revisions.
Last edited by JimEli; 5th Mar 2010 at 19:05.