Accelerate go, to 35ft, non FAR25 info. Max weight, flap up, nil wind and slope, 500 elevation, 20 degrees- 3800ft (1160m).
(a) I would have expected non FAR25 (ie FAR23) to be for 50 ft ?
(b) let me guess .. that distance is R mod data ?
(c) by comparison, for the standard OEM manual (for the earlier serials), accel-go at 12500lb and the same other details, ... gives a bit under 7000 ft. Climb gradient at 121kt is around 4.5% or a bit better. It's that speed thing that causes the problem ...
Interesting, is it not ?
why FAR 25 is relevant in a VH registered aircraft, operating on an increased weight STC operating to 20.7.1b
A bit of history is useful.
In the beginning (when the world was without form), the US did some sensible things such as have regs for certification and operations. DCA (the original precursor of CASA) came up with a rather strange amalgam of certification documents which either were stand alone or drew on the overseas (US or Brit) standards but with local tinkering at the edges which drove many in the local Industry to distraction. These, progressively and now, totally, have been consigned to the WPB-round. Ron Yates (ref The Yates' Report) had a bit to do with starting up some enthusiasm for getting this process finalised.
Operational documents, such as 20.7.1b, written by folks who didn't understand the certification documents, came up with a strange array of requirements which sometimes, but not always, mirrored the certification requirements. A far better approach would have been just to state .. observe the certification requirements. Great stuff for young engineers on both sides of the table who had to try and work it all out. I can't complain .. it made me a few dollars over the years ...
Back to the story ...
Courtesy of one of the posters, whom I know well but wasn't aware that he had changed his username, I now have a copy of the R STC .. will take some time to digest the rather large document. I am presuming that R has redone the basic performance work to be compliant with parts of Part 25. The FMS doesn't appear, explicitly, to state the certification basis (as is the usual case) so one would need to look at the STC package and associated certification data to form an opinion on that one. Depending on the detail in the FMS, it may/may not be open to claim compliance with all of 20.7.1b unless further data be sought.
For some years now, Australia has adopted the country of origin NAA approved AFM/POH as the book .. did I mention Ron Yates ? .. that's why FAR25 be relevant. The R STC has been signed off by an FAA delegate .. or so the front page states .. and it, thus, forms part of the FAA approved AFM/POH so that ties the two together.
Now, the loss of the various local certification documents resulted in the 20.7 docs having to relate to the foreign requirements .. otherwise we would have been in some sort of totally confused limbo. If you download 20.7.1b (makes it easier to search) and look for "flight manual", you will find a reference or two to "foreign flight manual" and lots of references to "flight manual". Now, I am a tad out of touch with the day to day activities in respect of flight manual approvals but, if I am correct, Australia no longer issues flight manuals for overseas sourced aircraft, requiring the owner to use the relevant foreign flight manual.
So, providing that the foreign STC does, in fact, meet the requirements of 20.7.1b, all should be fine and beaut. Just how do you know that it does .. when the foreign documents are based on the foreign design standards ? It may well do so .. but one ought not just to presume such is the case.
operating on an increased weight STC operating to 20.7.1b
Be careful .. the STC probably knows naught about 20.7.1b. At the end of the day, Australia is a bit of a backwater so far as the US Industry is concerned. Rather, it is the operator's responsibility to show that there is a compliance at audit. This is why I referred earlier to CAR(1988) 139(3) .. if your aeroplane doesn't carry the POH then you (as a pilot) are pretty well covered if you abide by the operator's Operations Manual. The problem then reverts to where it should lie .. with the operator/owner.
If it sounds like I am making a mountain out of a molehill .. I'm not ... it will be very interesting if and when a major prang leads to a Royal Commission and the lawyers really get stuck into all this stuff.