Aircraft engine certification FAR's

The information below comes from our resident informational
wellspring, Ron Wattaja. He stepped into a "debate" between Craig
Wall and an auto conversion believer and set the record straight about
what was and was not required in the aircraft engine certification
test with the following information. You will see by reading below
that the FAA requires a FAR (pun not intended) less rigorous test for
aircraft engines than Detroit does voluntarily for their street
engines. I say voluntarily, but Detroit understands that if they do
not produce engines capable of withstanding incredible abuse, the
buyers will go elsewhere and take their money with them and it will
take a long time to overcome the bad publicity, which tends to smear
all models.

*** Begin Quote ***

From FAR 33.49:

b) Unsupercharged engines and engines incorporating a gear-driven
single-speed supercharger....the applicant must conduct the following
runs:

(1) A 30-hour run consisting of alternate periods of 5 minutes at
rated takeoff power with takeoff speed, and 5 minutes at maximum best
economy cruising power or maximum recommended cruising power.

(2) A 20-hour run consisting of alternate periods of 1.5 hours at
rated maximum continuous power with maximum continuous speed, and 0.5
hour at 75 percent rated maximum continuous power and 91 percent
maximum continuous speed.

(3)A 20-hour run consisting of alternate periods of 1.5 hours at rated
maximum continuous power with maximum continuous speed, and 0.5 hour
at 70 percent rated maximum continous power and 89 percent maximum
continuous speed.

(4) A 20-hour run consisting of alternate periods of 1.5 hours at
rated maximum continuous power with maximum continuous speed, and 0.5
hour at 65 percent rated maximum continuous power and 87 percent
maximum continous speed.

(5) A 20-hour run consisting of alternate periods of 1.5 hours at
rated maximum continuous power with maximum continuous speed, and 0.5
hour at 60 percent rated maximum continuous power and 84.5 percent
maximum continous speed.

(6) A 20-hour run consisting of alternate periods of 1.5 hours at
rated maximum continuous power with maximum continuous speed, and 0.5
hour at 50 percent rated maximum continuous power and 79.5 percent
maximum continous speed.

(7) A 20-hour run consisting of alternate periods of 2.5 hours at
rated maximum continuous power with maximum continuous speed, and 2.5
hour at maximum best economy cruising power or at maximum recommended
cruising power.

That's 150 hours total, including 85 hours at maximum continuous power
and speed, and 15 hours at rated takeoff power. The longest runs at
max power are the 2.5 hour ones in para. 7. According to para (a) of
FAR 33.49, for at least 35 hours of the max runs, the engine must be
operated with one cylinder at redline temperature and the others
within 50 degrees of redline.

To my eternal shame, I don't have the regs that cover the primary
category. However, I seem to recall that they include reciprocity to
other country's certification rules. The CAM-100 engine, for
instance, was tested to JAR 22 (European motorglider) standards:
Fifty hours on the test stand, with short low-power cycles and 1-hour
full-power ones.

*** End of quote ***

Ron, I hope you will forgive me for re-posting this information you
dug up.

Corky Scott