X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 15 Aug 2011 23:20:20 -0400 Message-ID: X-Original-Return-Path: Received: from cgpro2.tulsaconnect.com ([65.38.1.5] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTP id 5093270 for lml@lancaironline.net; Mon, 15 Aug 2011 21:21:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.38.1.5; envelope-from=kent@tulsaconnect.com Received: from [65.38.9.183] (HELO main) by cgpro2.tulsaconnect.com (CommuniGate Pro SMTP 5.2.1) with SMTP id 74286077 for lml@lancaironline.net; Mon, 15 Aug 2011 20:20:53 -0500 X-Original-Message-ID: <50DD0F990B11401E94D577C71BBA44A5@main> From: "Kent" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Prop Balancing: Legacy X-Original-Date: Mon, 15 Aug 2011 20:20:53 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00F4_01CC5B88.D53FF480" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6109 This is a multi-part message in MIME format. ------=_NextPart_000_00F4_01CC5B88.D53FF480 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The Dynavibe is a good unit in concept. All Dynamic prop balancing = needs is an instrument to measure amplitude and phase angle, then a = scheme to correct any imbalance found. =20 But a FYI about the Dynavibe, when I looked at them couple years ago, = their vibration pickup had its cable integrated in one piece with the = MEMS sensor. If misfortune caused a cable to burn after touching an = exhaust pipe, one would have to send the whole cable and sensor back for = repair or replacement, which I was told was "several hundred dollars". Another thing I wonder about, Dynavibe provides a calibration = certificate but only after paying additional cost. =20 You think they would check each unit after assembly? Two channels is = also additional cost. =20 Generic balancing instructions found on the internet, and is applicable = for most piston aircraft and common turbines. Rule of thumb, use a 4 gram AN970-3 washer for each tenth IPS of = imbalnce. Move the test weight inboard for permanent attachment, added = another washer along with the bolt & nut. Hartzell has instructions for dynamic balance too. Hartzell does not = prohibit adjusting the shim static weights. regards Kent Felkins Tulsa ----- Original Message -----=20 From: paul miller=20 To: lml@lancaironline.net=20 Sent: Monday, August 15, 2011 6:40 AM Subject: [LML] Prop Balancing: Legacy Prior to my trip back to Calgary I wanted to get rid of a nasty = vibration. My last A&P actually made the balance worse and now that I = see the results I think it was 180 degrees out of phase. At 2300 rpm I = had a nasty shake. At Oshkosh I bought the simple Dynavibe unit from Spruce on sale. = Short story is I wasted a day misreading the procedure. In essence, you = measure "in the direction of prop direction" and I was moving the prop = in that direction to get the balance position. However, once that was = understood, I was able to get my prop dialed in from 0.63 to 0.03 in = fast order. It would not be hard to go further with a miniature weight = change but I wanted to fly. These are photos of the setup. If you ever decide to do this, it is = easy on the Legacy. You can mount everything on the inside of the cowl = which allows the runs to be made with cowls on. It also means leaving = all the cables in place when changing weights. I used temporary weights = on the spinner exterior to narrow things down form 0.63 to 0.16 which = took 4 large washers and about 16g net added weight on the spinner. At = that point, it only took two small washers (the type that are used to = fasten the spinner) to bring it down to 0.03. The final changes are = very very sensitive. By moving the last weights from one spinner screw = to another you can easily home in on the exact spot for final weight. That final weight was permanently installed on the spinner back and = the final weight was adjusted for the gram-inches between the final = radius and the temporary spinner radius. It worked out darn close. = The Dynavibe is not a feature rich machine but it does work well. I had = no problems. You must guess at the initial test weights but it only = takes a few quick runs to dial things in. It provides IPS at X degrees. = Simple. I made some brackets with spare parts sitting in the hangar. = I taped the cables to the airframe using 3M blue painter tape which held = during runup but pulled off clean. I coiled the wires on top of the = cowl so I could remove the cowl without disconnecting all the cables = each time. Big time saver. When my final weight was installed on the = spinner back plate I did a final run to verify the results and then = removed all the gear. The resulting 2000 miles back to Calgary was a big improvement. = Whereas I could not really cruise at 2300 before, it was now quite = smooth. I would recommend the procedure to anyone who wants to check = out their balance or verify an existing balance weight or remove a = vibration. I would note that the weights installed by Hartzell on the = hub underneath the spinner are NOT changed or tampered with. You can play the slideshow here Paul=20 Legacy Calgary ------=_NextPart_000_00F4_01CC5B88.D53FF480 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
The Dynavibe is a good unit in=20 concept.   All Dynamic prop balancing  needs is an=20 instrument to measure amplitude and phase angle, then a scheme to = correct any=20 imbalance found.  
 
But a FYI about the=20 Dynavibe, when I looked at them couple years ago, their vibration pickup = had its=20 cable integrated in one piece with the MEMS = sensor.    If=20 misfortune caused a cable to burn after touching an exhaust pipe, one = would have=20 to send the whole cable and sensor back for repair or replacement, which = I was=20 told was  "several hundred dollars".
 
Another thing I wonder about, Dynavibe = provides a=20 calibration certificate but  only after paying additional=20 cost.   
You think they would  check each = unit after=20 assembly?  Two channels is also = additional=20 cost.           &n= bsp;=20
 
Generic balancing instructions found on = the=20 internet, and is applicable for most  piston aircraft and common=20 turbines.
Rule of thumb, use a  4 gram = AN970-3 washer=20 for each  tenth IPS of imbalnce.   Move the test weight = inboard=20 for permanent attachment, added another washer along with the bolt & = nut.
 Hartzell has instructions for = dynamic balance=20 too.  Hartzell does not prohibit = adjusting=20 the shim static weights.
 
regards
Kent Felkins
Tulsa
 
 
 
 
----- Original Message -----
From:=20 paul = miller
Sent: Monday, August 15, 2011 = 6:40=20 AM
Subject: [LML] Prop Balancing:=20 Legacy

Prior to my trip back to Calgary I wanted to get rid of = a nasty=20 vibration.   My last A&P actually made the balance worse and = now that=20 I see the results I think it was 180 degrees out of phase.  At = 2300 rpm I=20 had a nasty shake.

At Oshkosh I bought the simple Dynavibe unit from = Spruce on sale.  Short story is I wasted a day = misreading the=20 procedure.  In essence, you measure "in the direction of prop = direction"=20 and I was moving the prop in that direction to get the balance = position.=20   However, once that was understood, I was able to get my prop = dialed in=20 from 0.63 to 0.03 in fast order.  It would not be hard to go = further with=20 a miniature weight change but I wanted to fly.

These are photos of the setup.  If you ever decide to do = this, it is=20 easy on the Legacy.   You can=20 mount everything on the inside of the cowl which allows = the runs=20 to be made with cowls on.  It also means leaving all the cables = in place=20 when changing weights. I used temporary weights on the spinner = exterior to=20 narrow things down form 0.63 to 0.16 which took 4 large washers and = about 16g=20 net added weight on the spinner.  At that point, it only took two = small=20 washers (the type that are used to fasten the spinner) to bring it = down to=20 0.03.  The final changes are very very sensitive. By moving the = last=20 weights from one spinner screw to another you can easily home in on = the exact=20 spot for final weight.

That final weight was permanently installed on the spinner back = and the=20 final weight was adjusted for the gram-inches between the final radius = and the=20 temporary spinner radius.  It worked out darn close.   The = Dynavibe=20 is not a feature rich machine but it does work well.  I had no = problems.=20   You must guess at the initial test weights but it only takes a = few=20 quick runs to dial things in.  It provides IPS at X degrees. =  =20 Simple.  I made some brackets with spare parts sitting in the = hangar.=20  I taped the cables to the airframe using 3M blue painter tape = which held=20 during runup but pulled off clean.  I coiled the wires on top of = the cowl=20 so I could remove the cowl without disconnecting all the cables each = time.=20  Big time saver.  When my final weight was installed on the = spinner=20 back plate I did a final run to verify the results and then removed = all the=20 gear.

The resulting 2000 miles back to Calgary was a big improvement.=20  Whereas I could not really cruise at 2300 before, it was now = quite=20 smooth.  I would recommend the procedure to anyone who wants to = check out=20 their balance or verify an existing balance weight or remove a = vibration.=20  I would note that the weights installed by Hartzell on the hub=20 underneath the spinner are NOT changed or tampered with.

You can play the slideshow here

Paul 
Legacy
Calgary
------=_NextPart_000_00F4_01CC5B88.D53FF480--