Originally Posted by B47
BTW - not to argue here, but I believe the first digits in an U.S.military aircraft serial number refers to the FY that the contract for that aircraft was signed and not the year it was built.
Tony always makes me think.
I needed to refresh my memory on how this worked.
I discovered the first two digits of the USAF Tail number is actually the Fiscal Year the particular aircraft was paid for (funded) and not when it was delivered (made) or the contract run was signed.
A multi-year contract can be signed, but each year's budget only funds the production authorized for that year. Thus a contract run can span more than on year. For example the 1961 Lockheed C-130E contract for 496 E Models spans tail numbers from 62-XXXX through 63-XXXX.
"Starting on July 1, 1921 (the beginning of FY 1922) a new serial number system was adopted based on procurement within each Fiscal Year. Each serial number now consisted of a base number
corresponding to the last two digits of the FY in which money was allocated to manufacture the aircraft, and a sequence number
indicating the sequential order in which the particular aircraft was ordered within that particular FY. For example, airplane 22-1 was the first aircraft ordered in FY 1922, 23-1 was the first example ordered in FY 1923, etc. This system is still in use today.
It is important to recognize that the serial number reflects the Fiscal Year in which the order for the aircraft is placed, NOT the year in which it is delivered. Nowadays, the difference between the time the order is placed and the time the aircraft is actually delivered can be as much as several years."
From: USASC-USAAS-USAAC-USAAF-USAF Aircraft Serial Numbers--1908 to Present
This only applies to Air Force Aircraft. Navy uses "Bureau Numbers" for example.
Learn something new every day...