Bolt info needed

If anyone is interested, I have seen a Brown Brothers Catalogue on eBay today!

The Brown Brothers (Aircraft) Ltd hardback catologue of Aircrft Standard Parts is the book to look out for.

Mark

Hi all, I would love to have a look at this book as I feel it would aid me in my understanding of British nuts/bolts etc which is what is used on My CAC Boomerang restoration….would anyone have a digital copy of this book available or able to copy for me ??

Many thanks,
Chris

[QUOTE=chiron A way of remembering the smaller British bolt shank diameters. A; 6 BA, B; 4 BA, C; 2 BA, E; 1/4 BSF, G; 5/16 BSF, J; 3/8 BSF, L; 7/16 BSF, N;1/2 BSF. ?All Boys Can Eat Good Jam, Leave None?, was passed on to me by one of those old world types I mentioned, it has proven useful, I just wish he?d had a better way to remember them!

Chiron[/QUOTE]

Now for the larger sizes;
P; 9/16″
Q; 5/8″
S; 3/4″
U; 7/8″
W; 1″

“Peter Quickly Slips Up Wendy” – never forgot that one!! 😀

Thanks Chiron,

Your keyboard – are you using multilingual settings? I get caught going from English to Russian sometimes.

A direct link to the CAP 562 download page

What a gem – the pdf is fully indexed, you are on the British bolt ID page in seconds.

– Hamtech.

hamtech

Save yourself the trouble, your reply spurred me into doing some digging on the UK CAA website. My reply referred to an outdated hardcopy version. I checked and it was Leaflet 2-3 (was as in, no longer current) however the same information is contained in CAP 562, as Leaflet 3-3. You will probably remember it is the one dealing with bolt identification (as opposed to BS / AN substitution) but is still an excellent overview.

Serves me right for living in the past.

For anyone interested, sorry I don’t have the link, but this publication is available as a 8 MB pdf file, under UKCAA Homepage / Publications / Aircraft Maintenance / CAP 562.

The real question though, is why did most of the punctuation marks in my last post change to question marks?

chiron

I suggest you talk directly with other owners of airworthy Geminies via The Miles Aircraft Collection (of which I believe you are a member) – eg Adrian Brook and Jim Buckingham in the UK. The only manufacturer’s literature available are the Repair & Service manual and the Pilot’s Notes (which does have some useful illustrations inside though I doubt if it goes as far as nuts and bolts). I have never seen a Miles parts manual in over 20 years of being interested in Miles a/c nor have I seen or heard of any surviving Gemini drawings (unless any Gemini owners acquired any with their aeroplane).

Today only a small number drawings exist for a few pre-war Miles designs. Unfortunately, I was reliably informed 20 years ago that the rest were apparantly all destroyed at Woodley sometime around 1970 – the successful engineering company that Miles Aircraft Ltd became postwar needed the storage space the drawings occupied so they were fed into the factory’s heating boilers! I guess nobody thought they were important to anyone else at that time, especially as so few Miles a/c were flying by then……

…from memory this leaflet was BL/2-3

mmm…I’m curious now, going to dig that one out on Monday!

Keep it original

How is the restoration progressing?

You will not find a non-original spec fastening or screw on either of my Miles aircraft. I have seen cross-head screws etc. on some restorations and these stick out like a sore thumb (ugh!).

Call Gordon Spooner, the restorer of the exquisite Messenger G-AJWB. A Messie is virtually a single-engined Gemini – you may find that he has boxes of everything you need and won’t need on his latest Navion project(!).

Good luck!

HP

Hi all. Long time listener, first time caller.

galdri
I would have replied much earlier but instead I?ve been working through a series of problems with the registration process. I can?t help wondering how many others are knocking on the door in vain, but that?s another story.

To answer your original question. Beg, borrow or steal a copy of the UK CAA Civil Aircraft Inspection Procedures, they contain a Leaflet on British bolt types, as well as hours of relevant reading for anyone in your situation, from memory this leaflet was BL/2-3 and there are others on ?AN? bolts, plumbing, materials etc. Between the CAIP?s and the LAS catalogue you should have 90% of the bolt substitution info you will ever need. Given the origin of the Gemini, you will sooner or later need access to the CAIP?s anyway. Ask around among local Licensed Engineers who work on British aircraft, or maybe a local University library, or your CAA or equivalent. A University library should also have copies of the British Standards Institution Specifications, which is where?A.1? and ?A.25?come from.
Reading between the lines I believe a higher priority though is to find an engineer who is intimately familiar with that era of technology, even if only to answer questions, rather than be involved in the actual certification. I?m sure your chap won?t mind taking suggestions from someone with relevant experience. The next step would be to make a point of being on first name terms with the equivalent of your local CAA (?) Airworthiness Inspector, they can be an absolute goldmine of information, both technical and administrative. A way of remembering the smaller British bolt shank diameters. A; 6 BA, B; 4 BA, C; 2 BA, E; 1/4 BSF, G; 5/16 BSF, J; 3/8 BSF, L; 7/16 BSF, N;1/2 BSF. ?All Boys Can Eat Good Jam, Leave None?, was passed on to me by one of those old world types I mentioned, it has proven useful, I just wish he?d had a better way to remember them!
The B.S. Spec?s 1952 index shows A.1 as ?out of print/obsolete?, but I don?t have access to an earlier copy. B.S. Spec. A.25 was published in Jan. 1950. The Gemini could not, therefore, have been built with A.25 bolts. (Which may take you back to ? it won?t be original anyway so why not use ?AN? bolts? – fun isn?t it!)
A.25 specifies the use of S.94, S.95 or S.96, and ?S.114 below 1/2 inch diameter?, these all being 55 ton UTS steels. There would likely be no technical objection to getting approval to use ?AN?, but run it all past your LAE first. If you want to research these steels they are also B.S. Spec?s.
Substitution of American ?AN? bolts into older British aircraft is certainly very common, but begs the question of the degree of originality you want. The A25 bolts are significantly more expensive than ?AN? but if you are only replacing a few defective ones as you go then the total cost may not be an issue. If you decide to use ?AN? you may have modification approval costs which negate any savings anyway. Decisions, decisions.

To cut a long story short Light Aero Spares are excellent to deal with and have a wide range, therefore I totally agree with the recommendations to go with British hardware if you can.

Hope this helps.

Chiron

I found the Light Aero Spares catalog excellent during my first steps in the british hardware jungle. LAeS used to have a ruler marked in 1/10th of an inch which i found handy when identifying bolts.

The Museum of Berkshire Aviation has/is restoring several Miles airframes to static condition. They might be able to help with info on parts lists and drawings.
http://www.fly.to/MuseumofBerkshireAviation
mmitch.

Is it the ale or have I’ve missed something?

Not at all, I did get the story the wrong way around. The experience has scarred me 🙂 Read, fit nut, cut to length, peen.

…the plain nut or half nut has been torqued

In this instance, American hardware including the self locking nut, British anachronism. Any “benefit” from peening disappears the first time you want to remove the nut!

Peening

That is two exposed threads after the plain nut or half nut has been torqued. 😉

Peening not to be used with ‘torque prevailing’ lock nuts.

One of the benefits of peening is the reduction in ‘stand out dimension’ compared with a correctly specified bolt plus lock nut.

Mark

Hi all,

If you are finding it hard to find the book shown above, it may be worth investing in a ‘Zeus’ book. This contains numerous data tables & information predominantly for machinists, but includes thread information along with tapping drill sizes etc. As an apprentice, this was somewhat of a bible. Here is a link to a site in Aus that sells it.

http://www.justtools.com.au/prod2065.htm

On another note, has using metric sizes been ruled out? I can see that American and British have some commonality, but in my opinion the availability of BS taps/dies etc will reduce and their price increase over the next few years. I mean, most of the world uses metric as the standard now.

For authenticity, obviously I would recommend to use the original bolt sizes/type.

Cheers,

James

On peening:

Recently rebuilding a “modern British aircraft” (its still under maintenance so best be vague here) we needed to replace a handful of bolts.

The drawing indicated to “Replace with an NASxxxx bolt” and then wait for it “cut the bolt until two threads are showing” (note the bolt in question comes in numerous lengths. “Install a self locking nut” great!, never seen one of those even so much as loosen but then the icing on the cake “peen to safety”.

Yes it has scarred me. One of many stories along the same lines. British designers must get sick of the many “dear god why?” questions ground engineers ask them 🙂

Too much beer to edit the quote, but the way that’s worded, you cut the bolt until two threads are showing and then fit a locknut. I assume only a qualified engineer would be doing the job and would know that’s ludicrous but that’s not what it says. Fit the locknut first, saw and then peen if you want to be over the top but if that’s really the way it’s specified it doesn’t work. With only two threads on the nut, it won’t reach the locking sytem.
Is it the ale or have I’ve missed something?

Despite spending may years flogging metals, I have never even heard of the aviation specs for bolts, etc. My experience was almost entirely commercial, not aerospace. However, I will add the following based on personal knowledge.
BSW/BSF taps, dies, spanners etc., are not a problem. British production cars were stil using these until well into the sixties. As a nation we seem resistant to change. I personally was making spring compressors using Whitworth studding (working for a company) in the early seventies. Even if nothing else has, the classic car movement has ensured the tools are still available.

American fittings are not direct subsitutes. I don’t know if one or two do actually fit but with diameter, pitch and angle to compare, there’s little likely to match.
Sir Joseph Whitworth is credited with inventing the first standard thread system, IIRC. I have no idea why this has stuck in my mind but I believe his threads were 55º and the majority of modern threads are 60º.

BSW/BSF spanners are not marked according to the distance accross flats like most other system’s, but by the thread size. A 1/4″BSW (3/16″BSF) is approaching 1/2″ AF. (I’m not going out to the garage to measure one at this time of night).

On peening:

Recently rebuilding a “modern British aircraft” (its still under maintenance so best be vague here) we needed to replace a handful of bolts.

The drawing indicated to “Replace with an NASxxxx bolt” and then wait for it “cut the bolt until two threads are showing” (note the bolt in question comes in numerous lengths. “Install a self locking nut” great!, never seen one of those even so much as loosen but then the icing on the cake “peen to safety”.

Yes it has scarred me. One of many stories along the same lines. British designers must get sick of the many “dear god why?” questions ground engineers ask them 🙂

Wow. And I thought it was just nail wooden a/c together! Good luck Mr.G. If an unqualified bod may stick a note in on the UK vs US hardware route; you might be smart to do an assesement of the options at this stage. Changing stuff to US on British a/c can cause problems, so I’ve been told. It’s also not original, and Miles nerds and their friends (deHavilland nerds etc… 😉 ) can be very picky about that at resale time… But I’m not an expert, so I’ll back off now.

On the cover of the catalogue. Oddie Nuts. Is that what they feed birds?

That’s very interesting AgCat. Would you happen to know when the change over from the A1 to the A25 specs took place?

Another thing. I’m having a blond moment 😮 What does peen-ing mean?

Galdri, not sure when the change took place but I am sure that the Gemini would have been specced with A1 bolts – that is what they used in those days.

Peening meeans that you use a plain nut on the bolt and to lock it to prevent it becoming loose in flight you deform the end of the bolt by burring the thread over with a hammer. Alternatively, the nut could be ‘staked’ at about four points around the thread circumference by burring the nut into the thread using a centre punch. Try to do that with an A25 high tensile steel bolt without proper support for the bolt and wooden structure can be easily damaged.

That’s very interesting AgCat. Would you happen to know when the change over from the A1 to the A25 specs took place?

Another thing. I’m having a blond moment 😮 What does peen-ing mean?

I do have a copy of the aforementioned book, and could copy it for you if need be.

Are extensive drawings still available? I am not a Miles expert, so dont know what is around. They would give bolt sizes. The only thing to note is that some of the numbers have changed since they were first produced – for example, A1 (Bolt) has become A25. There are cross references, or just ask!

Bruce

There is a trap here. If the Gemini was specced with A1 bolts, take care when substituting A25. The A1 bolt was sized by overall length. The A25 bolt is sized by the length of the plain shank. This is an issue which affects old DH aircraft such as the Tiger Moth. There is an approved mod to change from A1 to A25 bolts on the Tiger and other Moth aircraft, but care is needed in the substitution. Care is also needed if the method of locking is by peening. A25 bolts are much harder than A1 bolts, and if peened wrongly, wooden structure can be easily damaged.