Jerry Wass wrote:
To what standards are today's(and/or yesterdays) A/C engines corrected
to???

I find the older SAE J607--60°F---29.92" Hg 0% humidity
SAE J1349--77°F 29.234"Hg 0%
DIN 68°F 29.92
JIS 77°F 29.234 0%
?? J1995 77°F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry

I sincerely doubt it was the J607 standard used to rate the engines
since if you actually read the J607 standard you will see that it
clearly states that it was developed for basically lawnmower engines(
50 ci displacement and 20hp) You will also see that it allows for only
a ten percent correction to be applied. A real hoot when you see it
applied to a 500hp supercharged engine. However your question seems to
be what is the standard day used for calculations, rather than the
calculations applied, so I will say I believe the FAA uses standard day,
standard atmosphere at sea level with zero humidity calculated by the
formulas defined in the US Standard Atmosphere 1976 standard(Temperature
= 15°C, specific humidity = 0.00 kg H2O/kg dry air, and pressure =
101325 Pa). I also believe that this standard is largely in agreement
with the international standard at near sea level altitudes that you are
concerned with.

As far as what standard was in effect at the time a particular engine
was certified, I can't tell you. There are versions of the US Standard
Atmosphere going back to 1958, and I do not know what correction factors
were applied.

The FAA engine certification tests are more rigorous than the typical
dyno run and require an endurance test that includes the following regimes:

(1) A 30-hour run consisting of alternate periods of five minutes at
takeoff power and speed, and five minutes at maximum best economy
cruising power or maximum recommended cruising power.

(2) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 75 percent maximum continuous
power and 91 percent maximum continuous speed.

(3) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 70 percent maximum continuous
power and 89 percent maximum continuous speed.

(4) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 65 percent maximum continuous
power and 87 percent maximum continuous speed.

(5) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 60 percent maximum continuous
power and 84.5 percent maximum continuous speed.

(6) A 20-hour run consisting of alternate periods of 1½ hours at maximum
continuous power and speed, and ½ hour at 50 percent maximum continuous
power and 79.5 percent maximum continuous speed.

(7) A 20-hour run consisting of alternate periods of 2½ hours at maximum
continuous power and speed, and 2½ hours at maximum best economy
cruising power or at maximum recommended cruising power

I will bet that many of the un-certified engines being marketed out
there couldn't finish the endurance test without swallowing an exhaust
valve.


Charles