RE: [DOG mailing list] Hoffman propeller HO-V62-R / Issues withchanging positon to cruise

[kristinnowell]

Hi Jarek,

With our newish prop (280 hours, also with aSN that starts with A), we shift 
into cruise at about 1800-2000 rpm, and find that when in flight (as opposed to 
pitch changes on the ground during run-up), the pull requires a bit more force, 
but the lever should only come out about 2-4 cm. I would describe the pull as 
steady but not sharp and not particularly slow. Kristn just uploaded a short 
video of me this https://m.youtube.com/watch?v=VyYbV802UAM
   Tom

Sent from my Windows 10 device

From: Jarek Steliga
Sent: Sunday, October 14, 2018 13:57
To: dog@lists.riverland.net.au
Subject: Re: [DOG mailing list] Hoffman propeller HO-V62-R / Issues 
withchanging positon to cruise


Tom and Nigel,

Perhaps that's where the shoe pinches? Perhaps the manner I pull the pitch 
change handle needs to be looked into before other reasons are examined (shaft 
runout or two bearings not touching the driven plate simultaneously). It is 
unlikely that serious mechanical malfancions occur just a year since that 
particular prop had been released by Hoffman from overhaul, with the time of 
actual use not exceeding 20 hours. 

I have to admit that I always pulled the handle all the way and  only now 
having read your remarks realize that perhaps that was completely wrong. Can 
the handle be pulled slowly untill the drop of RPM occurs or does it have to be 
a shorter but energetic jerk?

Is the jury out on the RPMs at which the pitch change should be made? Is it 
2200 or between 1800 and 1900 or what? Which works best for you?


Regards

Jarek






 
 

niedz., 14 paź 2018 o 14:03 Nigel Baker  napisał(a):
Hi Jarek I checked the Hoffman Prop manual and indeed you are correct.
However all on this list will say 2200 RPM I think.
Expect a drop of 200 rpm for cruise so aim for a drop of 250 momentarily. The 
idea is to provide enough clearance for the slide to move into place in the 
Centre stem nut shoulder without the RPM dropping so far that the centrifugal 
force drops so much the slide will not stay out in the cruise position.
It is a balancing act between RPM and hand force on pull handle.
As Tom says if you pull the change handle far enough back it will rumble like 
hell as the blades are stalling due to too high an angle of attack. It won’t do 
any damage but is unnerving.
This takes a little finesse but once mastered you will find it easy enough.
 
Nige.
 
 
 
 
From: dog@lists.riverland.net.au  On Behalf Of Tom 
Preisser
Sent: Sunday, October 14, 2018 8:19 AM
To: dog@lists.riverland.net.au
Subject: Re: [DOG mailing list] Hoffman propeller HO-V62-R / Issues with 
changing positon to cruise
 
Perhaps you are pulling the handle too far out ? Just pull it a little, because 
if you pull it too far the prop will rumble, the rpm will fall too much, and no 
change to cruise will happen.
Let us all know what you discover.

On Friday, October 12, 2018, Rob Thompson  wrote:
> 1-  Normally the RPM on change should be 2200 to go into cruise.
> 2 - Sounds like the pitch change/feather plate on the rear of the prop is not 
> running true or alternatively the two bearings that contact it are not 
> touching at the same time.
> Use a finger dial guage to check if the plate is true.
> regards
> Rob
> Rob Thompson
> 0429 493 828
> (Please note that my new email address is amessageto...@gmail.com)
>
> On Sat, Oct 13, 2018 at 6:53 AM Jarek Steliga  wrote:
>>
>>
>> Hello,
>> I am quite new here (have owned Dimona for only 3 months). 
>> Despite scrupulously folliowing the instructions regarding the required 
>> RPM-s of between 1800  to 1900 at which the propeller pitch is changed from 
>> START to CRUISE in midair, I have only succeedded twice despite numerous 
>> attempts. Also pulling the pitch lever in the cockpit results in scary 
>> vibrations which discourages me from continuing my trial and error methods. 
>> Can someone please help?
>>
>> Best regards
>> Jarek
>>   


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RE: [DOG mailing list] Hoffman propeller HO-V62-R / Issues withchanging positon to cruise

[kristinnowell]

The Hoffman Prop Service Bulletin E34 rev B. (attached) that underlies both the 
EASA and FAA ADs is more clear in it's explanation that the blades in question 
are of pre-1983 manufacture. They also note that with these older design 
blades, no power on aerobatics are allowed. I guess that means with our 1998 
“A” design (rounded tip style: HO-V-62 R/L160BT) we’re good to go try some!

Kristin

Sent from my Windows 10 device

From: Laurie Hoffman via dog
Sent: Saturday, October 13, 2018 18:21
To:; Rob Thompson; dog@lists.riverland.net.au
Subject: Re: [DOG mailing list] Hoffman propeller HO-V62-R / Issues 
withchanging positon to cruise

While carrying out a daily inspection a couple of years ago, I was surprised to 
discover a lot of vertical movement at the prop tips. 
Up till then I'd focussed more on lateral tip movement but since then I make a 
thorough check of both.
Laurie

Sent from Yahoo7 Mail on Android

On Sun, 14 Oct 2018 at 9:14 am, Rob Thompson
 wrote:
That is the old style props which didn't have enough lag screws to safely hold 
the blades in.
Make sure you check the silicone seal on the inner blade where it goes into the 
hub. If a blade is coming out the silicon splits and you can see a definite gap 
in the silicone.
Rob

Rob Thompson
0429 493 828
(Please note that my new email address is amessageto...@gmail.com)


On Sun, Oct 14, 2018 at 8:58 AM Michael Stockhill  wrote:
Tom, and others,

The FAA just issued an airworthiness directive AD on Hoffman props used with 
Limbach 2000. It requires any blades that do not have an A or B suffix to the 
serial number to be replaced. It deals with possible loss of a blade, and the 
number and size of the retaining screws.
 
I dodged that bullet

M

On Sat, Oct 13, 2018, 3:48 PM Tom Preisser  wrote:
Perhaps you are pulling the handle too far out ? Just pull it a little, because 
if you pull it too far the prop will rumble, the rpm will fall too much, and no 
change to cruise will happen.
Let us all know what you discover.

On Friday, October 12, 2018, Rob Thompson  wrote:
> 1-  Normally the RPM on change should be 2200 to go into cruise.
> 2 - Sounds like the pitch change/feather plate on the rear of the prop is not 
> running true or alternatively the two bearings that contact it are not 
> touching at the same time.
> Use a finger dial guage to check if the plate is true.
> regards
> Rob
> Rob Thompson
> 0429 493 828
> (Please note that my new email address is amessageto...@gmail.com)
>
> On Sat, Oct 13, 2018 at 6:53 AM Jarek Steliga  wrote:
>>
>>
>> Hello,
>> I am quite new here (have owned Dimona for only 3 months). 
>> Despite scrupulously folliowing the instructions regarding the required 
>> RPM-s of between 1800  to 1900 at which the propeller pitch is changed from 
>> START to CRUISE in midair, I have only succeedded twice despite numerous 
>> attempts. Also pulling the pitch lever in the cockpit results in scary 
>> vibrations which discourages me from continuing my trial and error methods. 
>> Can someone please help?
>>
>> Best regards
>> Jarek
>>   



SBE034_B.pdf
Description: Adobe PDF document

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RE: [DOG mailing list] Maine Dimona H36 flying videos

[kristinnowell]

I’d love to exchange  our ❄ for some of your  and balance things out!


Sent from my Windows 10 phone

From: Laurie Hoffman via dog
Sent: Sunday, February 4, 2018 8:49 PM
To: dog@lists.riverland.net.au
Subject: Re: [DOG mailing list] Maine Dimona H36 flying videos

Hi Kristin,
Great videos!
I'm just wondering what that white stuff is in many of them though!

Best Regards
Laurie 





On Saturday, 3 February 2018, 4:50:27 am AEDT, Kristin Nowell 
 wrote: 


Dear Dimona owners,

I have been playing around making music videos of flying in the H36 around 
Maine, those of you in the heat down under especially might appreciate a taste 
of winter ops:

https://www.youtube.com/user/tkxmix/videos?sort=dd=0_id=0

I'm no Rob Thompson professional producer, but having fun!

Cheers,

Kristin (and Tom)

[DOG mailing list] Low oil temps in the cold New England air.

[kristinnowell]

Hi all,

I’m thinking of covering up the front face of the oil cooler as we are seeing 
persistently low oil temps barely off the redline even with the engine at full 
throttle (prop in cruise) given how cold it is around here now (-7C). Maybe 
fabricate an aluminum plate and safety wire in place? Any thoughts suggestions 
advice.?

Tom

Sent from my Windows 10 phone

Re: [DOG mailing list] Spins

[kristinnowell]

Thanks very much for your help, guys.  Nige, the aero restrictions on SB 12 
came in earlier (Jan 1985).  The wing failure from a July 1986 accident in 
Germany indeed was the result of acc to the investigation  high g loading - at 
high angles of attack.  Wolf Hoffmann further said to Tom awhile back 
commenting on this that the LBA wanted them to “do something” even if no 
structural imperfection was found, thus the SB 19 winglatch kit.  We got the 
original accident summary from the BFU database, it doesn't say much, but it 
does say this:


Accident in Walchensee on 29.07.1986

Aircraft wing related event (ATA Code:5700) , during Cruise. {Occurrence}
Fuselage main bulkheads (ATA Code:5312)
Wing attachment fitting (ATA Code:5740)


Weather conditions VMC

Aircraft SN 36115  D-KESL

Aircraft total time 820 Hours *flying club

crew experience This Aircraft type 17 Hour(s)
All types 1198 Hour(s)


Events: primary break of the right wing in the flight (SE) - cruising (D1) |_ 
FUSELAGE/BULKHEADS (70BA) |_ Not
sufficiently firm/solid (88H4) |_ WINGS/WING ATTACHMENT FITTINGS, BOLTS (70AC) 
|_ Not sufficiently firm/solid
(88H4)







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From: ni...@limbachaustralia.com
Sent: ‎Saturday‎, ‎June‎ ‎25‎, ‎2016 ‎10‎:‎41‎ ‎AM
To: dog@lists.riverland.net.au







Yep. I have had it go in unintentionally a couple of times while soaring in 
thermal conditions. A good gust brought it on both times. It is quite benign 
and relaxing back stick is enough to get a quick recovery from the start of an 
incipient. I have deliberately done it once to see what it is like although 
didn’t let it fully develop. Again I would describe it as a bit benign. Easy 
recovery and no noticeable hesitation. I did it intentionally with 1 up but the 
other 2 times were 2 up. All 3 times were at about half fuel load. It isn’t 
what I would say as prone to spinning IE doesn’t drop in at the drop of a hat.

Hope that is of help.

I thought the Aero  restrictions came in after the catastrophic wing failure 
from Gross Overload during Aero’s and thus SB19.

Cheers.

Nige.

 



 


From: Kristin Nowell 

Sent: Saturday, June 25, 2016 10:30 AM

To: dog@lists.riverland.net.au 

Subject: [DOG mailing list] Spins

 
 


Hi all,

Our glider aerobat friend (Unlimited!) is coming to Maine for vacation, and is 
keen to fly in Tom's Dimona. Has anyone ever (unintentionally) spun it? 
Originally it was certified for aerobatics but then came 1985 SB 12 ( "Due to 
irregularities observed at spinning, further tests will be performed and until 
then the placard must be installed), like what kind of irregularities? And 
either the tests were not done or not satisfactory as this operating 
restriction was never lifted, unlike those of service bulletin 18 ("glider 
flying prohibited!" "dual controlled instruction flights only"!), which were 
removed upon install of the wing latch kit (SB 19).

Thanks Kristin