Hi Dan,
Comments interspersed below.
WRB
On Nov 18, 2009, at 16:53, Caliendo Dan wrote:
Can't argue with your premise; but we all also learn from each others
opinions.
Agree 100%! Opinions have a place so long as their basis is reasonable
and shared, and so long as they are not presented as fact.
Obviously you have
a better tach than I do because my needle vibrates over a 50 rpm
range. I have considered putting in
a digital next annual. For those of us who have old tachs that
vibrate, we are stuck with judging a mag
drop from our "perception" ....which I admit is subjective.
Dan C
Here are some of my opinions ;<)
Even though such judgment is subjective, it can serve the purpose
intended. Most of us can "perceive" clearly and instantly the RPM drop
of a four cylinder Continental that is airworthy, i.e. adjusted to and
operated within manufacturer's recommended specs. if we sit with our
eyes closed and have another pilot go through normal "mag. check" runup
procedures. Accordingly. such RPM drop could not be described as
"imperceptible".
As to how to "read" a tach that "vibrates", even with a 50 RPM "range
of needle vibration", a 50 RPM drop from dual mag. to single-mag
operation would then be bouncing between tach markings 50 RPM lower.
Such a difference should be visually perceptible to the careful
observer because it is present or absent at the flick of the (mag)
switch. Sometimes such "vibration" is caused by tach cable wear or
lack of periodic lubrication.
I do believe getting into such detail serves a valid purpose by
promoting further consideration and evaluation to a procedure many
perform by just going through the motions (as they were trained to do)
without the slightest idea why the mag. check is important and what is
being verified by such process.
The pilot who understands "why" as well as "how" is infinitely better
equipped for any unexpected situation as may arise.
On Nov 18, 2009, at 3:04 PM, William R. Bayne wrote:
Hi Dan,
You're certainly welcome to disagree, but it's more productive to
debate objective points (as opposed to subjective ones).
