Mailing List lml@lancaironline.net Message #53360
From: J H Webb <airmale@windstream.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] unfeathering accumulator question
Date: Tue, 03 Nov 2009 08:21:37 -0500
To: <lml@lancaironline.net>
Mark,
With a free turbine, there is absolutly no problem unfeathering the PT6. This engine is unique in that you can feather it and still have the engine running providing the aircraft with power due to the free turbine design.  I have flown the PT6 in a vast number of aircraft including the Lancair IVP. I have flown this engine doing Expemental Flight Test inclyding Know Iciing testing. It is a smooth light engine that does not require an unfeathering accumlator unless you want to unfeather the prop in flight without the engine running. But I cannot think of a reason to do this as the drag rise is very substantial.

Jack Webb
L360, LIV
Former Chief Engineering Test Pilot
BSAE


From: Mark Ravinski <mjrav@comcast.net>
To: lml@lancaironline.net
Sent: Mon, November 2, 2009 12:32:41 PM
Subject: [LML] unfeathering accumulator question

Turbine types,
I met a fellow yesterday who is building a Seawind with a 550 hp PT-6.  It is complete except for paint.
He says he will not be able to unfeather the prop in flight if there is no oil pressure.  (engine not running)
It seems I've read here on the LML that some turbines are equipped with unfeathering accumulators.
Can anyone enlighten me about that for a PT-6?
 
Thanks,
He really loved a ride in my 360.
 
Mark Ravinski
1479 hrs
----- Original Message -----
Sent: Monday, November 02, 2009 7:51 AM
Subject: [LML] Re: AOA Calibration Questions

Posted for John Hafen <j.hafen@comcast.net>:

 Gents:
 
 Hopefully someone on the list knows way more about my AOA than I do.  Thanks
 in advance for your assistance.
 
 Running through the AOA PRO II Calibration Check List, in the Cruise
 Configuration Calibration, the checklist says:
 
 Zero G Maneuver for 1/2 second:         YES
 
 The next line says:
 
 PTT Red Record Button                    PUSH/RELEASE
 
 My question:  Am I to assume that you push the Red PTT button during the 1/2
 second of Zero G Flight?  After?  When?
 
 You also have to do some button pushing at 1.15 of Clean stall, and
 1.15 of dirty/landing configuration stall.
 
 Having not repeatedly stalled my IVP while looking closely at the airspeed
 indicator, I admit I can¹t say exactly what the clean and dirty stall speeds
 are, although the numbers I have been able to glean are that an IVP should
 have a clean and dirty stall speed of 80 and 75 KIAS respectively.
 
 So to calibrate the AOA, I would be pushing the buttons at 92 and 87 KIAS
 for clean and dirty.
 
 Is there any reason to calibrate at higher speeds than 92 and 87?  Would you
 get an earlier warning of an impending stall?
 
 Your advice and comments are very welcome.
 
 Regards,
 
 John Hafen
 IVP 413AJ ‹ 200 hours


[The AOA records the data at the release of the PTT button, so you can press it when you start the maneuver and release it at the instant you are satisfied that you are performing the required maneuver.   <marv>   ]

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