AerostarDriver Posted March 21, 2021 Report Posted March 21, 2021 I am at the firewall forward section of what seems to be a "5 year plan" of an annual. In trying to pull the suction screen we found that one of my engine mount bolts (on the airframe side) is not an AN4-27A like it is called out in the parts manual but rather a same sized non aircraft bolt. In an attempt to match the parts manual, I need an AN365-428 however, spruce has an AN365-428A. Does anyone know the difference between the two? Quote
MB65E Posted March 21, 2021 Report Posted March 21, 2021 An An365 is the nut. Not a bolt. some of the older hardware doesn’t have the goldish cad plating we are used to seeing. It was more of a nickel cad back then. Need a pic of the bolt you are describing. Circle the bolt in question -Matt 2 Quote
carusoam Posted March 21, 2021 Report Posted March 21, 2021 Since there are only four tiny (specialized) bolts holding the 200 horse to the firewall... It is a good idea to make sure you get the right hardware... AS usually has the right hardware... But, their catalogs can’t keep up with their inventory... If their inventory doesn’t keep up... AS has a solution for that too... They have awesome customer service people... you may have to speak with them on the telephone... Best regards, -a- Quote
Mooneymite Posted March 21, 2021 Report Posted March 21, 2021 1 hour ago, AerostarDriver said: I am at the firewall forward section of what seems to be a "5 year plan" of an annual. In trying to pull the suction screen we found that one of my engine mount bolts (on the airframe side) is not an AN4-27A like it is called out in the parts manual but rather a same sized non aircraft bolt. In an attempt to match the parts manual, I need an AN365-428 however, spruce has an AN365-428A. Does anyone know the difference between the two? From Aircraft Spruce QnA: Q: What is the difference between a AN365-428C and an AN365-428A? The C designates stainless steel. The A will be cad plated steel. Q: What does it mean when you dont have the letter A at the end -AN365-xxxA -? The A nuts will be cad plated steel. Quote
AerostarDriver Posted March 21, 2021 Author Report Posted March 21, 2021 1 hour ago, MB65E said: An An365 is the nut. Not a bolt. some of the older hardware doesn’t have the goldish cad plating we are used to seeing. It was more of a nickel cad back then. Need a pic of the bolt you are describing. Circle the bolt in question -Matt The bolt installed is gold in color but lacking the correct stampings on it. For .85 cent it is not worth keeping it. 22 minutes ago, Mooneymite said: From Aircraft Spruce QnA: Q: What is the difference between a AN365-428C and an AN365-428A? The C designates stainless steel. The A will be cad plated steel. Q: What does it mean when you dont have the letter A at the end -AN365-xxxA -? The A nuts will be cad plated steel. I just am looking to understand what the difference is between the non-letter designated hardware and the A for the AN365-428. Maybe a better question is can an AN365-428A be a substitute for an AN365-428? Does it matter if they are nylocs or a metallic lock insert? One side of the top engine mount hardware has a metal type insert and one has a nylon. In my case I am trying to achieve like factory or better. 1 Quote
carusoam Posted March 21, 2021 Report Posted March 21, 2021 17 minutes ago, AerostarDriver said: The bolt installed is gold in color but lacking the correct stampings on it. For .85 cent it is not worth keeping it. I just am looking to understand what the difference is between the non-letter designated hardware and the A for the AN365-428. Maybe a better question is can an AN365-428A be a substitute for an AN365-428? Does it matter if they are nylocs or a metallic lock insert? One side of the top engine mount hardware has a metal type insert and one has a nylon. In my case I am trying to achieve like factory or better. substitutions require a healthy bit of knowledge... If using a nyloc nut in an environment that destroys nylon... this would be bad... You probably won’t find too many nylon inserts under the cowling... Even though nylon parts do show up in there in places like mags... In the ‘how important is it category...’ a simple washer can have a huge affect on how well something stays torqued down... certain hardware is selected by the environment that it lives in... Often times... this hardware is a single use item that can cost hundreds of dollars... others are just pennies... Two notable hardware failures we see from time to time... 1) V-band clamps that hold exhaust system parts together... when improperly re-used... they fail and fall off... leaving a blow torch affect behind... 2) Star washers... when re-used they don’t work as originally intended... they don’t lock, and the nut comes loose... leaving a mag loose and dangling, while the oil drains out... Often, the engine manufacturers have spent years determining what works where the best... there can be thousands of combinations... they publish their recommendation... going outside this recommendation has got to have some good logic behind it... You just don’t want something that should work or may work to be holding important things together... Great questions, keep asking! PP thoughts only, not a mechanic... Best regards, -a- Quote
Mooneymite Posted March 21, 2021 Report Posted March 21, 2021 16 minutes ago, AerostarDriver said: The bolt installed is gold in color but lacking the correct stampings on it. For .85 cent it is not worth keeping it. I just am looking to understand what the difference is between the non-letter designated hardware and the A for the AN365-428. Maybe a better question is can an AN365-428A be a substitute for an AN365-428? Does it matter if they are nylocs or a metallic lock insert? One side of the top engine mount hardware has a metal type insert and one has a nylon. In my case I am trying to achieve like factory or better. It appears Spruce has your answer. The A may, or may not be appended. Either is plated steel. They are the same. If followed by the letter C, it is stainless steel. Quote
carusoam Posted March 21, 2021 Report Posted March 21, 2021 If we are discussing the bolts that holds the engine mount to the airframe... (?) You want exactly what is recommended... a bolt that looks identical... may be strong in one direction or the other... Good in shear, but not good in tensile strength... Getting a stainless bolt may sound good... But, when you check its ratings for strength... it may fail under a lighter load... So... if still discussing mounting the engine to the airframe... Get the right hardware... You will never know why somebody else put a different bolt in a 50year old airframe... If aircraft Spruce doesn’t have it... there are several aviation hardware supply houses listed around here... There is also Dan at Lasar that can be super helpful for this task... The firewall is an important place for having things go awry... some engine mounts have been torqued down with carpet or insulation in the way... Best regards, -a- Quote
Guest Posted March 21, 2021 Report Posted March 21, 2021 There’s nothing exotic in the hardware, just run of the mill AN steel with cadmium plating. Quote
JRo Posted August 29, 2021 Report Posted August 29, 2021 On 3/21/2021 at 1:29 PM, Mooneymite said: It appears Spruce has your answer. The A may, or may not be appended. Either is plated steel. They are the same. If followed by the letter C, it is stainless steel. @Mooneymite where did you see that note on Aircraft Spruce? Quote
mike20papa Posted August 29, 2021 Report Posted August 29, 2021 (edited) "A" suffix means there is NO hole drilled in the shank (or the head, either) Now, that means you have to use a stop nut vs. a castellated nut (no cotter pin). The next decision is what kind of stop nut. AN365-428 is an elastic stop nut (nylon insert vs all metal) Edited August 29, 2021 by mike20papa Quote
Guest Posted August 30, 2021 Report Posted August 30, 2021 AN365 series nuts are obsolete, they are now MS21044N…. Clarence Quote
A64Pilot Posted August 30, 2021 Report Posted August 30, 2021 Not to be argumentative, but C means corrosion resistant, which may or may not be stainless steel. In this case if there is any doubt whether it’s aircraft hardware by all means replace it. Quote
cliffy Posted September 2, 2021 Report Posted September 2, 2021 AN364 Series Specifications Nut - Self Locking, Thin, 250° F (a) Minimum A not specified. Limited only by strength requirement of specification. For definition and application of drawing status note see ANA bulletin No. 337. Add “A” after dash number for nuts having non-metallic inserts. Add “C” after dash number for nuts fabricated entirely from metal. Examples of part numbers: AN364-428 = 1/4-28 steel nut, either all metal or with non-metallic insert. AN364D428 = 1/4-28 aluminum alloy nut, either all metal or non-metallic insert. AN364B428A = 1/4-28 copper base alloy nut with non-metallic insert. AN364-428C = 1/4-28 steel nut, all metal. Nylon insert nuts have a limitation of 250 degrees ALL metal lock nuts ("shake proof") have no such limitation Quote
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