Question for the techo's (LAME etc)

[VH-XXX]

Came across this recently. RA-Aus have mandated the installation of manifold guages on aircaft with constant speed or in-flight adjustable props.

Do you think this would be required based on the comments? Do they put undue stress on an engine? This includes electrically adjustable in-flight units on many aircraft.

http://www.auf.asn.au/airworthiness/AN200808-1.doc

I can't see CASA issuing a statement like this:

Background:
Some recent reports have highlighted problems with aircraft engine crankshafts failing having been placed under abnormal stress from the In-flight Adjustable propeller in flight.

Action Required:

• On or before the next periodic inspection fit a manifold pressure gauge to all aircraft fitted with constant speed or flight adjustable propellers.

[Mr Milk]

How bout "on or before next periodic, burn aircraft to the ground and get something less dangerous like a proven engine/airframe"

[VH-XXX]

You just keep thinking that next time you're banging around in your 1969 Cessna bucket of corrosion.

[Horatio Leafblower]

XXX

That's a certified bucket of corrosion with an extensive, world-wide fleet maintained under mandatory maintenance and reporting procedures by Government qualified personnel.

Not a brand-new collection of old Ice-cream containers glued to some old Al tubes with the motor from the old Ride-on strapped to the front flown by a bloke who was taught by his mate who has a PPL and is therefore the most experienced and senior member of the Club

...and besides CASA wouldn't need to issue a SB like that because 99 times in 100 the aircraft was designed, built and certified with enough forethought to prevent such nasty surprises.

[Spodman]

I don't have a constant speed endorsement, but how would you know what you are asking of your engine without a manifold pressure gauge? Sounds fair enough to me.

If CASA had issued this instruction it would not be the next periodic inspection, it would be before the next flight, even if you are across the country where there don't happen to be any manifold pressure gauge shops around.

[Jabawocky]

Who was the donkey who fitted an electric CSU (most likley), and not MAP indication of some sort?

Stupid SB's like this only appear after a greater act of stupidity...... from either CASA or the RAA

J

[homeless1]

so fit a manifold guage, and then if your Rotax spins at say 5000 rpm, then you could run it to 50 inches map !

what's wrong with that ?? it aint oversquare......

[Jabawocky]

50MAP

And this over square thing...... is an old wives tale

Stop spreading the rumour! Even the engine manufacturers can not understand where it came from. Apart from some very old radials where the limits were easily remembered that way.

Chinese whispers!

Now watch all the fur fly!

J

[ZEEBEE]

When specifying a propellor match (FPitch) to an engine the aircraft manufacturer is required to demonstrate that the engine cannot be overloaded to the point of detonation over the the whole of the range of engine speed and TAS.
With a variable pitch prop, all bets are off.
The whole concept of a variable pitch prop is to allow the engine to be operated within a much narrower range of propellor/engine load parameters.
This allows the combination to stray into the detonation area if not operated correctly.
The only way to ensure the correct operation is to monitor the MAP vs RPM parameters laid down by the manufacturers and stay within the prescribed limits.
can't see how else that can be achieved without a MAP gauge unless going to automatic controls...

Or get a Diesel

[carbon]

Who was the donkey who fitted an electric CSU (most likley), and not MAP indication of some sort?

Exactly!

How do you set standard power settings on a CSU equipped machine without a MAP gauge?

Regardless of regulatory requirements or engine limitations, quantifying the torque level your engine(s) are developing is highly important!