Today's Message Index:
----------------------
1. 07:06 AM - Prop hub stud torque (Jill Gernetzke)
2. 07:03 PM - Re: Prop hub stud torque (Walter Lannon)
3. 10:17 PM - Re: Prop hub stud torque (Royden 2011)
4. 11:16 PM - Re: Prop hub stud torque (Royden 2011)
Message 1
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| Subject: | Prop hub stud torque |
Just saw this post and thought I should correct some bad information. The
torque value specified in the Russian V-530 Overhaul manual (Dated 14 May
1975) for the six prop hub studs is 7 (+1) kgc-m. (50 - 57 ft/lbs - if
Online Conversion is correct.) This is significantly different than 87.
I have never heard of a stud breaking on a V-530 hub, but I have now.
Jill
M-14P, Inc.
Message 2
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| Subject: | Re: Prop hub stud torque |
Hi Jill;
I believe Eric's 87 lb/ft for the V530 prop. retaining nuts is correct.
I use 82 to 93 lb/ft. Can't remember where it came from but it fits for the
bolt size and the engine HP. Hartzells & McCauleys on 150- 180 HP require
50 ft/lb.
MT propellors (for over 300HP and with 9/16" studs) require 100 to 110
lb/ft.
57 lb/ft is the correct torque for the V530 and J9-G1 blade clamp nuts.
Walt
----- Original Message -----
From: "Jill Gernetzke" <jill@m-14p.com>
Sent: Tuesday, May 10, 2011 7:03 AM
Subject: Yak-List: Prop hub stud torque
>
> Just saw this post and thought I should correct some bad information. The
> torque value specified in the Russian V-530 Overhaul manual (Dated 14 May
> 1975) for the six prop hub studs is 7 (+1) kgc-m. (50 - 57 ft/lbs - if
> Online Conversion is correct.) This is significantly different than 87.
>
> I have never heard of a stud breaking on a V-530 hub, but I have now.
>
> Jill
> M-14P, Inc.
>
>
>
Message 3
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| Subject: | Re: Prop hub stud torque |
Hi Jill,
Please post all the other propeller torque number that you quoted to me on
the phone yesterday that came directly from the V-Perod Propeller overhaul
Manual.
Safety is the name of the game here - Your reference to "bad" information
is a euphanism for unsafe and dangerous information.
Gorillas at the end of torque wrenches may well lead to stud failure.
Please set the record straight for the misinformed.
Royden
----- Original Message -----
From: "Jill Gernetzke" <jill@m-14p.com>
Sent: Tuesday, May 10, 2011 7:03 AM
Subject: Yak-List: Prop hub stud torque
>
> Just saw this post and thought I should correct some bad information. The
> torque value specified in the Russian V-530 Overhaul manual (Dated 14 May
> 1975) for the six prop hub studs is 7 (+1) kgc-m. (50 - 57 ft/lbs - if
> Online Conversion is correct.) This is significantly different than 87.
>
> I have never heard of a stud breaking on a V-530 hub, but I have now.
>
> Jill
> M-14P, Inc.
>
>
>
Message 4
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| Subject: | Re: Prop hub stud torque |
Dear Yaklisters
This is an appeal please to not rely on personal belief or equivalence to
North American propellers/practice.
The Russians built these very successful and robust V-530 props for
decades - let's go by their manual. That they have evidently been seriously
over-torqued (~60%) in the USA without previous reports of failures is a
testament to their robustness.
Jill's conversion is correct.
7 kg.m = 50.6 ft.lb
8 kg.m = 57.9 ft.lb
As for stud size: - what you see in NOT what you get. The stud nut is 22 mm
and one sees only thread exposed when the prop is off the aircraft.
But being on the receiving end of a broken stud one finds a stud shank that
is wasted to a diameter noticeably less than the inside diameter of the
thread - and always hidden from view when normally within the prop flange.
Why the designers do that, I can only guess. Presumably because the spline
carries all shear loads and the stud is designed to carry only tensile
loads. By wasting the shank, it will not attract shear loads from the holes
through which it loosely passes in the prop hub.
The specified torque must be based on the wasted shank diameter (normally
hidden from view) and not the larger thread that is normally in view. Hence
the deceivingly low torque values specified by the Russians for these studs.
If Jill posts all the torque numbers, you will find the specified torque
for the prop blade c clamps is higher than the for the flange studs (59
ft.lb if I remember well). Maybe not surprising as the shank diameter for
the C clamp bolt visually appears larger than the wasted diameter of the
prop flange studs. (However, to be confirmed with measurements next
weekend).
I also hope to get you some photos showing the failed stud by next weekend.
Please take care and be vigilant with your torque wrenches!
Royden
----- Original Message -----
From: "Walter Lannon" <wlannon@persona.ca>
Sent: Tuesday, May 10, 2011 7:00 PM
Subject: Re: Yak-List: Prop hub stud torque
>
> Hi Jill;
>
> I believe Eric's 87 lb/ft for the V530 prop. retaining nuts is correct.
> I use 82 to 93 lb/ft. Can't remember where it came from but it fits for
> the bolt size and the engine HP. Hartzells & McCauleys on 150- 180 HP
> require 50 ft/lb.
> MT propellors (for over 300HP and with 9/16" studs) require 100 to 110
> lb/ft.
>
> 57 lb/ft is the correct torque for the V530 and J9-G1 blade clamp nuts.
>
> Walt
>
> ----- Original Message -----
> From: "Jill Gernetzke" <jill@m-14p.com>
> To: <yak-list@matronics.com>
> Sent: Tuesday, May 10, 2011 7:03 AM
> Subject: Yak-List: Prop hub stud torque
>
>
>>
>> Just saw this post and thought I should correct some bad information.
>> The
>> torque value specified in the Russian V-530 Overhaul manual (Dated 14 May
>> 1975) for the six prop hub studs is 7 (+1) kgc-m. (50 - 57 ft/lbs - if
>> Online Conversion is correct.) This is significantly different than 87.
>>
>> I have never heard of a stud breaking on a V-530 hub, but I have now.
>>
>> Jill
>> M-14P, Inc.
>>
>>
>>
>>
>>
>>
>>
>
>
>
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