Reflects the local certification standard. The US stall speed based climb limit was replaced by the Oz OEI requirement .. more payload. Bit long ago now for the details to be fresh but, as I recall, Sleighs did the upgrade so it was probably Bob M or Rudy P doing the certification work.
The Oz OEI / STC was undertaken by Jim Wilson & Ron Smith at Executive Air Services in the late 1960's/early 70's. Bob Mac was a performance engineer with DCA then and had a bit to do with it. He later worked at Execs.
Jim was the best boss I ever had in GA - was sad to see him pass on. That was long before Sleigh Aviation got involved with EAS. Things changed when they lost the Air Amb contract to Bill Suhr around 78 and then Sleigh's got the coastwatch contract, initially with Shrikes.
The STC was meant to be the property of EAS, but due to some glitch in the paperwork (??) it applied without limit to all the AC500's at the time and since.
There was a VFR and an IFR weight established under the Oz STC and the a/c would perform if flown correctly. I recall some flight testing undertaken for en-route SE climb at 5000ft around that time, even on the Grand Commander. I think some operators think they can fly it at 7400lb all day every day but that is not in accordance with the STC unless VFR. I recall the IFR wt was 7150lb (? long time ago!) My experience on the Shrike was that 7150lb was workable and catered for a critical engine failure. At the time it catered well doing charter and air ambulance (mostly below those weights).
There was one famous occasion when during training at Tulla (before it opened to airlines) a Shrike did a touch & go with an EFTO and the instructor expected it to be aborted, but the student flew out of it due to what he thought was following traffic. The word was that he climbed out from EF at 65kts. The instructor let it run as there was plenty of runway and the a/c was performing - obviously not at a high weight!
Had many hours in the Shrike and loved every minute of it (.. ok, except for a couple of self-induced frights that shouldn't have happened).
John T, I agree with you, also having some 4000 hrs on Shrikes and other AeroCom models. Naturally, the self-induced frights were a thing of the time (or our experience!)
Would be happy to own and fly one now in retirement!!
