Engine mount to fuselage bolts

How to keep the Cessna 170 flying and airworthy.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

Engine mount to fuselage bolts

Postby 1moretw » Wed Jul 06, 2022 11:00 am

The bolts holding my engine mount to the fuselage are not all the same. Some have castellated nuts and some don't. Additionally, the nuts are all on the inside of the fuselage. Is there a standard for direction of the bolt and the type of nut (metal locking, fiber locking or castellated)? One of the bolts is even too short so no threads protrude.
User avatar
1moretw
 
Posts: 25
Joined: Sat May 28, 2022 11:29 am

Re: Engine mount to fuselage bolts

Postby c170b53 » Wed Jul 06, 2022 1:31 pm

4629CE81-E2E1-45BE-80E6-ED389D4863B5.jpeg

TW, welcome to the association and the forums. Please let us know what model, year you’re flying one more time! Do you have the IPC ?
Above the bolts on a “B”. General rule, nuts to the pilot but not always. Having the right bolts generally works best :D
Thks for joininh
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
User avatar
c170b53
 
Posts: 2404
Joined: Mon Apr 22, 2002 8:01 pm
Location: Vancouver B.C.

Re: Engine mount to fuselage bolts

Postby Bruce Fenstermacher » Wed Jul 06, 2022 4:32 pm

You have a lot of questions to answer.

Direction of the bolt. As specified, as depicted or head towards direction of flight or direction of rotation are the rules that come to mind. So first a maintenance manual may specify the direction. Next a IPC or maintenance manual may depict the bolt in a direction though be careful IPCs are seldom approved sources. Last head in the direction of travel or rotation so in theory if the nut came of or the bolt sheared, the bolt or parts left of it may stay in place holding parts together.

More later as I have time.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email:
N7A '49 170A -More original than most making folks GREEN with envy
N42532 '45 J-3 Clipped Wing Cub
User avatar
Bruce Fenstermacher
 
Posts: 10053
Joined: Tue Apr 23, 2002 11:24 am
Location: Telford, PA Based at UKT

Re: Engine mount to fuselage bolts

Postby 1moretw » Wed Jul 06, 2022 10:47 pm

Thank you, thank you for the picture from the parts manual. Never gave it a thought re looking at the manual.
By the way, my 170 is a 1952 170B N2674D
User avatar
1moretw
 
Posts: 25
Joined: Sat May 28, 2022 11:29 am

Re: Engine mount to fuselage bolts

Postby Bruce Fenstermacher » Thu Jul 07, 2022 12:40 am

More. There is no difference in strength of a standard AN bolt whether it is drilled for a cotter pin or not. It is improper however to us a drilled bolt with a mechanical locking nut and it would be weaker if you did and the mechanical locking nut was over or outside the drilled hole. The castellated nut, there are several kinds, and cotter is just a method of locking the nut in place.

Mechanical locking nuts come in all steel pinching and fiber insert type. General rule is the all steel versions would be used anyplace the fiber type might be destroyed by heat. Generally you don't find fiber nuts firewall forward. The exception is of course if a fiber nut is specified forward of the firewall by an IPC Our C-145/0-300 have a few fiber nuts specified on the engine by the manufacturer and so while contrary to the general rule, could not be questions as being correct. Few would find it a problem replacing fiber locking nuts with metal type but not necessarily the other way around.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email:
N7A '49 170A -More original than most making folks GREEN with envy
N42532 '45 J-3 Clipped Wing Cub
User avatar
Bruce Fenstermacher
 
Posts: 10053
Joined: Tue Apr 23, 2002 11:24 am
Location: Telford, PA Based at UKT


Return to The Hangar

Who is online

Users browsing this forum: No registered users and 22 guests