Propeller/Annual Inspection

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MoonlightVFR
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Propeller/Annual Inspection

Post by MoonlightVFR »

Does an annual inspection require cutting the safety wire and removable of each prop bolt to be
in compliance with an annual inspection?

Simple 2 blade fixed prop with no AD notes. Simple
gradyb, '54 B N2890C
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GAHorn
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Re: Propeller/Annual Inspection

Post by GAHorn »

It depends.

If there is reason to suspect that a prop strike or corrosion or cracks exist beneath the hub or on the crankshaft prop-flange, then the area should be inspected.

The basic guidance for an annual inspection is found in Appendix D of Part 43. Paragraph (h) applies, where subpara (1), (2) addresses inspecting for cracks, nicks ... and Bolts for improper torqueing and lack of safetying.

However, ordinarily, Lacking indications that the above have existing deficiencies, ... propellers are not ordinarily removed in Part 91 operations except at engine overhaul, when the bolts, flange faces, hubs etc are inspected in more detail in accordance with prop mfr's instructions.

If you have no suspicion of damage or corrosion and see no evidence of defects in a visual inspection and the prop has been properly installed and logged as such... then if you and your inspector disagree as to whether or not it should be disassembled.... you have the option of requesting that area of the inspection not be performed, and that ITEM being listed as an outstanding discrepancy in a "list" given to you, a copy being kept by the inspector.
He/She will have the right to state in the logs that the inspection was completed EXCEPT for the items not performed to their satisfaction. They will make no entry of approval for returning the aircraft to service. (But no entry denying approval for return to service will be made.)
YOU may then have another A&P (IA not req'd) look at the item in question, and if he so chooses, he/she may sign off that part of the inspection, and approve it for return to service.

Remember, your IA doesn't have to approve the aircraft for return to service except under his own subjective judgment... but he is not permitted to make derogatory logbook entries with regard to that inspection. He either competes the inspection and approves it for return to service with an entry... or he does not. You always have the option to have another do that.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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canav8
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Re: Propeller/Annual Inspection

Post by canav8 »

DUring an annual, safety wire is removed and bolts are retorqued. The reason for it is possible bolt stretching. So the answer is only a thorough IA will do that. You will not get that done with a $300 annual.
52' C-170B N2713D Ser #25255
Doug
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johneeb
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Re: Propeller/Annual Inspection

Post by johneeb »

canav8 wrote:DUring an annual, safety wire is removed and bolts are retorqued. The reason for it is possible bolt stretching. So the answer is only a thorough IA will do that. You will not get that done with a $300 annual.
Doug, do you have a wooden prop?
John E. Barrett
aka. Johneb

Sent from my "Cray Super Computer"
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jlwild
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Re: Propeller/Annual Inspection

Post by jlwild »

I have mine inspected every other annual. That's so the spinner bulkhead can be checked for cracks.
Jim Wildharber, Kennesaw, GA
Past President TIC170A (2010-12) and Georgia Area Representative
'55 170B, N3415D, SN:26958, O-300D; People's Choice '06 Kelowna, B.C., Best Modified '07 Galveston, TX, Best Modified '08 Branson, MO.
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canav8
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Re: Propeller/Annual Inspection

Post by canav8 »

johneeb wrote:
canav8 wrote:DUring an annual, safety wire is removed and bolts are retorqued. The reason for it is possible bolt stretching. So the answer is only a thorough IA will do that. You will not get that done with a $300 annual.
Doug, do you have a wooden prop?
Yes, on my RV-6. But bolt retorquing is a standard practice on metal props also. Wood props have to me done more often and that is not due to bolt stretching.
52' C-170B N2713D Ser #25255
Doug
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GAHorn
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Re: Propeller/Annual Inspection

Post by GAHorn »

The McCauley Overhaul Manual 730720 states in para. 1-11 that..."The propeller mounting bolt torque should be checked at least once a year."

However no comment regarding method or technique is made. I would like to point out that a dry bolt, torqued to specification, will not likely turn or rotate without exceeding the torque originally specified. This is because the bolt will have friction-resistance to resist further turning at the specified torque. Any torque range specified (such as 800-1000 in lbs) would be checked to it's maximum (1000) value, but if that has occurred repeatedly, the bolt will be unlikely to move due to the resident friction.

Safety wire, torque-seal, tab-washers, etc. are common methods of determining that a fastener has not appreciably loosened in-service, and that is why many, if not most inspectors do not cut the wire and re-torque bolts. The correct mounting bolts will not stretch under normal use (because they are sized and designed for the specific service. If they stretch...they are incorrect or have been damaged.) Only if some damage or catastrophic event will cause those bolts to stretch, and that injury will be obvious from other evidence such as prop-strike damage, etc.

The 100 Series Service Manual, 1962 and Prior applies to our 170 aircraft.
Section 2 , pg 15 addresses propeller inspection. Item 1 only states "Fixed-pitch propeller for track, nicks, corrosion, bends, dents, security, and proper safetying."

What it might take to satisfy any particular inspector's curiosity with regard to "corrosion" or "security" is subjective. If he/she feels they must remove the propeller to inspect for corrosion behind the hub... then one must either allow that or refuse that.

As for "proper safetying"... my EM series prop on my O-300-C engine has no safety wire at all. Security is dependent upon fiber-lock nuts behind the crankshaft flange. Each annual involves applying a torque wrench to the bolts and seeing they do not rotate. If my airplane were stored outdoors in a wet, seaside climate, I might see why it would be necessary to remove it occasionally to check for corrosion.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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c170b53
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Re: Propeller/Annual Inspection

Post by c170b53 »

Does an annual inspection require cutting the safety wire and removable of each prop bolt to be
in compliance with an annual inspection?
Well obviously the answer is ...maybe.
As George mentions, its subjective. If the person doing the inspection has never seen the plane before and has reason to think there's an issue then I guess they might want to dive in.
It shouldn't take much effort or time to do this job and as Jim mentioned back plates do crack.
As for the McCauley Overhaul Manual 730720 ref as George knows, not all props are McCauley's and a manufacturers recommendation on a part is just that, the liability would rest with the aircraft's manufacturer's inspection requirements.
With a prop hub, if corrosion can be detected early then likely it can be addressed before significant damage can occur thus cost wise, I'd have it looked at on a regular basis.
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
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canav8
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Re: Propeller/Annual Inspection

Post by canav8 »

Aryana wrote:The Waddington Effect comes to my mind on this one. My IA and I don't remove those bolts unless the prop is being refinished or overhauled.
Id hate to look at your spinner backplate.
52' C-170B N2713D Ser #25255
Doug
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lowNslow
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Re: Propeller/Annual Inspection

Post by lowNslow »

Aryana wrote:The Waddington Effect comes to my mind on this one. My IA and I don't remove those bolts unless the prop is being refinished or overhauled.
I agree, I feel like I'm putting more wear and tear on my aircraft taking it apart and putting it back together again every year. Waddington Effect at work.
Karl
'53 170B N3158B SN:25400
ASW-20BL
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GAHorn
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Re: Propeller/Annual Inspection

Post by GAHorn »

c170b53 wrote:... As for the McCauley Overhaul Manual 730720 ref as George knows, not all props are McCauley's .....
Exactly. The point I was trying to make is there are more than ONE source for reference on most inspection items. The Airframe mfr'r has valuable input on what areas require inspection. In fact, the airframe mfr'r has the most authority on such matters... but the appliance mfr's have specific info on how to accomplish service on their product. BOTH should be consulted when servicing/inspecting.
Cessna might tell us to inspect the generator... but DELCO-REMY (or whoever made yours) is who tells us HOW to do it. That's why I quoted both sources as an example. (As Jim points out, obviously if you have a different branded product you should consult that mfr's procedures and recommendations.)

Look guys... in my first response to this question,... in my first sentence... I gave you all the DEFINITIVE ANSWER!


(It depends.) :wink:
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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ghostflyer
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Re: Propeller/Annual Inspection

Post by ghostflyer »

During my initial training I spent 2 years working in a prop shop [many years ago] while it was interesting but very dirty so this is where I gained some knowledge . I have only had one prop depart a aircraft and I didn't fit it . With a fixed pitch prop all mating surfaces are cleaned and coated with ARDROX AV30 and this is wiped to provided a very thin coat . The prop is fitted with NDI inspected bolts and torqued to manufactures specs and procedures. They are then wire locked and then using a witness paint or a brightly colored nail polish a dot is placed on the bolt head and prop. This dot of paint will show if a prop bolt is moving or stretching as the wire locking will allow some movement . The core of the prop Prop and interior of exposed crankshalf is then coated AV30 for corrosion protection. The prop stays on and bolts only checked torque if witness paint appears broken .
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MoonlightVFR
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Re: Propeller/Annual Inspection

Post by MoonlightVFR »

I like the prior post . Ghostflyer.

Witness paint. One dot per bolt at juncture of bolt head and crankshaft flange. If paint fractures and shows
bolt head movement then it is time to intensify the inspection.

Sounds reasonable but I am sure it is not required.

For my part I am not in favor of wearing out the fasteners in my airplane for an "inspection".

Is "component disassembly" part of language in annual inspection regulations ?
gradyb, '54 B N2890C
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