Suitable material for replacing sand-cast 356-T6 fitting

[jd750ace]

What would be the best material to machine a replacement from for a sand-cast 356-T6 attachment fitting for a flight control surface?

 

[boo1]

Depends on compexity and requrements:
Possible A356-T6 or 367-T6

check guide at:

http://www.mid-atlanticcasting.com/alum-casting-alloys_FEB05.pdf

 

[SAITAETGrad]

A cast flight control fitting? Sounds suspect. Are you sure it isn't forged after casting?

MMPDS-01 Table 3.9.4.0(b) provides allowables. Suggest 6061-T651 per AMS-QQ-A-250/11 or AMS-QQ-A-200/8 due to superior strength, near identical stiffness, excellent machining, corrosion, fatigue, cost, etc.

 

[jd750ace]

It is on a Constellation. Elevator attach, control side. I had arrived at 6061 T6 for the same reasons, and near identical weight, although it is not a balance concern. It will be no problem to machine.
Thanks for the responses.

 

[tbuelna]

jd750ace,

As noted by SAITAETGrad, 6061-T651 wrought aluminum would be a good choice as a direct material substitution for sand cast 356-T6. 6061-T651/AMS 4027 wrought material has better mechanical Ftu/Fty properties than sand cast 356.0-T6/AMS 4217 (42ksi/36ksi vs. 22ksi/15ksi), plus the wrought material would also have better fatigue properties. You could also take into account the large analysis knock-down factors typically applied to cast aircraft structures.

I've attached a historical version of FAR 25.621 from 1965 showing the casting factor requirements. The Connie design is much older than that, but it still gives a useful perspective.

Hope that helps.
Terry

 

[MikeHalloran]

Whoa!

Where did you get a Constellation in flying condition?



Mike Halloran
Pembroke Pines, FL, USA

 

[berkshire]

Are you part of Save-A-Connie or did your plane start its new life as part of a Restaurant
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[epeus]

Whoa!

Where did you get a Constellation in flying condition?

Are you part of Save-A-Connie or did your plane start its new life as part of a Restaurant
B.E.

this is possibly the one - down here in oz we fly all the good oldies

[URL unfurl="true"]http://hars.org.au/[/url]

 

[tbuelna]

Here's a great website dedicated to Lufthansa'a ground-up restoration of a Super Connie:

http://www.dlbs.de/en/Projects/Lockheed-Superstar/News.php

Imagine what this project costs!