AS350 Start Procedure - Hydraulic Test

[ReverseFlight]

I had the same experience many moons ago training for my endorsement when the slightest brush from my hand on the collective during the hydraulic test was sufficient to spring the plate to its unsecured position but fortunately my instructor noticed it and wasted no time in pushing the collective down to keep her on the pad.

Subsequently I always had my hand pressing aft on the spring plate instead of trying to hover my hand over the collective in anticipation of a jump.

[Seismic Pilot]

Hyd test B2

I think there is some misconception about flight idle and ground idle.
Ground idle is when the machine has just been started and is sitting at 70% ng.Flight idle is when its sitting on the ground at 100% RRPM or in the case of an astar 394 rrpm at flat pitch.

[JimEli]

Thanks for pointing out the idle misconception, my post is corrected.

[bellsux]

Eurocopter Telex's TFS 142 for the B2 and TFS 153 for the B3 which can be found on TIPI make for good reading on the AS350 Hydraulic system.

[oldbeefer]

Company I worked for has a fleet of BBs. The check is done at 100% Nr. Local orders require the catch to be on, the friction to be on and the pilot to hold the lever througout the check. The last two were introduced after a student managed to slip the catch, the lever rose 'cos he wasn't holding it, aircraft tipped onto its tail - no damage luckily!

There can be variations in terminology eg:

Squirrel - Flight Idle - throttle fully open.

Bell 412 - Flight Idle - throttles at idle

[arismount]

For What It's Worth

At a previous company the habit was to complete the start and get it stabilized at 70% with the FCL, and remain below the flight gate until putting it up just before takeoff. Saved a little fuel and some noise. But I remember the check airman saying that at the factory school, all the training pilots completed the start, pushed the lever up to the flight gate (100% Nr) and then did all the checklist items from there.

[victor papa]

I agree with the flight idle position. the fLM is not 100% clear, but as said before if you read the whole procedure you do find yourselve in flight idle before the check is asked for. I have seen some pilots who do the ACCU TEST until the accumulator runs down and the control goes hard for some reason or others do big movements on the cyclic instead of the 10% travel asked. If you are at ground idle the starflex and spherical bearing is not offloaded by centrifugal force and in my opinion if you do the above you are overloading both in a situation they are not designed to handle.

[What Limits]

We are currently communicating with Eurocopter to get some guidance on this whole subject.

I will let you know what we find out. As they say in Canada "Good luck with that!"

What concerns me is that all over the world, there is a lack of understanding as to what we are trying to acheive during this test, what can go wrong and also how to do it. Again, some RFMs seem to be amended and some don't.

[idle stop]

On the EC120 (similar hyd system to 350) a few years ago EC changed the check-list so that the ACCU and manual control Hyd OFF checks are done at ground idle prior to opening the 'throttle' to flight idle. Previously they were done as per the general interpretation of the current AS350 checks, ie nominal flight NR.
Bell, on the other hand, have standardised the checks across a number of types: HYD(s) Off (in turn) and check no unacceptable kicks at ground idle, plus cross-system interlock checks; then check of acceptable manual control forces at 100% NR.
If you're going to get a nasty surprise it's better at ground idle than flight idle, but checking the acceptablility of control forces in manual at flight NR is not bad idea.

(Sp edit)

[HELIHARRY]

FM Procedures

Greetings What Limits.

Your topic is one that has always made me ask questions and I can see where you are going with this despite the confusion with %s of this and that. What I think you are talking about is whether or not to do the test at ground idle or flight idle and which version of the flight manual (PMV) says what i.e some say to perform the hydraulics test prior to advancing the lever to flight idle and most say to do it once flight idle is achieved.

There are several valid points in this thread, particularly where the FM specifically directs us to perform the test at flight idle when in fact conditions underfoot do not make this a safe operation. For this reason I think a number of operators choose to have an SOP which specifies conducting that part of the start up procedure at "ground idle". There is also the valid point of ensuring the logic of the horn function of the test and the fact that hydaulic pressure will not be consumed at the same rate (ground idle vs flight idle).

All very valid points and makes me wonder why operators have SOPs which contradict the flight manual, i.e do the hydraulic tests at ground idle rather than flight idle.

I believe there are flight manuals floating around which are supposedly of the latest revision status but do actually differ. I have flown the D, B, BA, FX and B2 and have found the manuals to differ in the start up procedure.

I believe it is the intention of the manufacturer to have us doing this test at flight idle in all later model aircraft (or at least flight manuals) but when adverse conditions exist I also believe it is good airmanship to ensure system functionality at ground idle.

p.s after many years of consuming the information on this site this topic has made me burst into print so go easy on me this time, I am here to learn. HH

[JimEli]

I believe it is the intention of the manufacturer to have us doing this test at flight idle in all later model aircraft (or at least flight manuals) but when adverse conditions exist I also believe it is good airmanship to ensure system functionality at ground idle.

That is exactly opposite of what I read in versions of my (current) flight manuals. See my above post.