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