F-1 Engine MD Changes

The F-1 rocket engine was not a single, off-the-shelf product; rather, the engine was constantly tweaked and its configuration frequently updated, either as the result of a customer request or a suggestion by the manufacturer to simplify construction or to address issues they encountered. Engine changes began as an "engineering change request (ECP)" and approved changes were implemented as an "MD change" (I've never seen an explicit explanation of what "MD" stood for, but I did read something which seemed to imply that it was "model designation").

Some changes were major configuration changes, while others were relatively minor. Some engines were originally manufactured after the change had been implemented and so the change was incorporated in the engine as it was shipped from the factory, while other engines were retrofitted with the change in the field. Other changes were not deemed important enough to warrant the expense of retrofitting engines.

Regardless of the source or magnitude of the change, it was necessary to keep track of which changes had been applied to which engines. In addition to the importance of good record-keeping (which, of course, NASA loved), installation and checkout procedures sometimes had to be updated as a result of specific engine modifications. Thus, it was necessary for technicians to know what MD changes had been incorporated in a particular engine.

To this end, engines bore an identification plate documenting which MD changes had been incorporated. As it turns out, during the F-1 production run, there were two different types of ID plates documenting MD changes (one wonders whether the change to the ID plate corresponded to an MD change!).

F-1 rocket engine RD171-1022 MD change plate

Click image for a 2019x1876 pixel version of this image in a new window.
From p. xvi of the F-1 Rocket Engine Technical Manual: Engine Data (R-3896-1), located in the archives of the U.S. Space & Rocket Center. Also available from the NASA Technical Reports Server.
Scan by heroicrelics.org.

The MD identification symbol and the equipment model designation indicated the configuration of the engine and distinguished it from models incorporating different changes and from basic models. A basic, unchanged configuration of the engine had no MD identification symbol. MD identification symbols were added as changes affecting configuration were incorporated. The MD identification symbol was stamped on the MD plate, which was mounted near the engine nameplate.

On MD identification plate RD171-1022-0001, above, the identification symbol was a composite number representing all the changes affecting configuration (MD changes) incorporated or not incorporated into the engine. The symbol represented a consecutively-numbered series of MD changes. Any MD change, or series of MD changes, not incorporated was represented by an "X." Multi-digit numbers were underlined. Two figures together represent the limits of a series of incorporated MD changes.

See F-1 engine F-4028 at the U.S. Space & Rocket Center for an example of an F-1 with the RD171-1022-0001 MD identification plate.


F-1 rocket engine RD171-1052 MD change plate

Click image for a 2019x1876 pixel version of this image in a new window.
From p. xvi of the F-1 Rocket Engine Technical Manual: Engine Data (R-3896-1), located in the archives of the U.S. Space & Rocket Center. Also available from the NASA Technical Reports Server.
Scan by heroicrelics.org.

MD identification plates RD171-1052-0001 through -0006, above, had pre-printed numbers from 1 through 100 on the -0001 plate, 101 through 200 on the -0002 plate, etc. Modifications that were incorporated into the engine were represented by the letter P (production) or K (kit) stamped in the square directly to the right of the applicable number. The lack of a P or K indicated that the MD change was not incorporated in the engine. A P or K with a bar marked through it (i.e., P, K) indicated that an MD change was deleted in its entirety by the incorporation of a later MD change.

See F-1 engine F-6045 at the U.S. Space & Rocket Center for an example of an F-1 with the RD171-1052-0001 MD identification plate.


Approved F-1 ECP Numbers and Corresponding MD numbers

Here's a table of approved F-1 engineering change proposal (ECP) numbers and their corresponding MD change numbers, as of 12 May 1972. The F-1 Rocket Engine Technical Manual: Engine Data (R-3896-1), which describes the F-1 rocket engine, had to be updated for many MD changes, and the table also lists the issue date of the manual which was updated for the MD change.

Approved
ECP No.
MD No. Incorporated in
Manual Dated
F1-38 37 17 May 1965
F1-38R1 -- N/A
F1-39 11 8 June 1964
F1-40 -- N/A (superseded by F1-254)
F1-42 7 8 June 1964
F1-45 7 8 June 1964
F1-56 7 8 June 1964
F1-57 7 8 June 1964
F1-59 7 8 June 1964
F1-60 16 N/A
F1-62 7 8 June 1964
F1-64 7 N/A
F1-65 7 8 June 1964
F1-67 10 8 June 1964
F1-69 7 8 June 1964
F1-71 9 8 June 1964
F1-74 7 8 June 1964
F1-76 24 27 October 1964
F1-76R1 -- N/A
F1-78 7 8 June 1964
F1-80 7 8 June 1964
F1-82 18 8 June 1964
F1-85 7 8 June 1964
F1-86 7 8 June 1964
F1-90 7 8 June 1964
F1-91 7 N/A
F1-95 7 8 June 1964
F1-97 7 8 June 1964
F1-98 20 N/A (superseded by F1-197)
F1-99 14 8 June 1964
F1-100 7 8 June 1964
F1-101 8 8 June 1964
F1-106 7 8 June 1964
F1-108 7 8 June 1964
F1-124 7 8 June 1964
F1-129 8 N/A
F1-129R1 -- N/A
F1-131 7 N/A
F1-132 7 8 June 1964
F1-135 7 8 June 1964
F1-143 11 8 June 1964
F1-143R1 -- N/A
F1-146 1 8 June 1964
F1-147 7 8 June 1964
F1-149 11 27 October 1964
F1-153 7 N/A
F1-154 7 8 June 1964
F1-166 13 8 June 1964
F1-168 8 8 June 1964
F1-169 7 8 June 1964
F1-172 7 8 June 1964
F1-174 21 N/A
F1-174R1 -- N/A
F1-176 22 N/A
F1-180 34 27 October 1964
F1-182 7 N/A
F1-185 32 11 May 1964
F1-185R1 -- N/A
F1-188 7 27 October 1964
F1-188R1 -- N/A
F1-189 7 27 October 1964
F1-191 7 27 October 1964
F1-192 46 28 September 1965
F1-192R1 -- N/A
F1-192R2 -- N/A
F1-193 7 27 October 1964
F1-193R1 -- N/A
F1-194 7 27 October 1964
F1-195 7 27 October 1964
F1-196 29 N/A
F1-197 20 27 October 1964
F1-198 26 N/A
F1-198R1 -- N/A
F1-202 7 27 October 1964
F1-206 22,66 27 October 1964
F1-206R1 -- N/A
F1-206R2 -- N/A
F1-208 33 27 October 1964
F1-214 31 28 September 1965
F1-214R1 -- N/A
F1-215 116 8 August 1966
F1-215R1 -- N/A
F1-215R2 -- N/A
F1-216 31 N/A
F1-216R1 -- N/A
F1-217 7 N/A
F1-226 35 N/A
F1-228 36 27 October 1964
F1-229 8 27 October 1964
F1-229R1 -- N/A
F1-233 38 28 September 1964
F1-235 31 N/A
F1-236 7 27 October 1964
F1-241 7 27 October 1964
F1-242 39 27 October 1964
F1-244 7 27 October 1964
F1-251 7 27 October 1964
F1-253 43 N/A
F1-254 7 27 October 1964
F1-255 42,45 N/A
F1-258 22 27 October 1964
F1-258R1 -- N/A
F1-258R2 -- N/A
F1-260 54 N/A
F1-260R1 -- N/A
F1-260R2 155 N/A
F1-261 22 17 May 1965
F1-262 50 N/A
F1-263 51 N/A
F1-267 49 17 May 1965
F1-268 59 17 May 1965
F1-268R1 -- N/A
F1-269 55 17 May 1965
F1-270 47 28 September 1965
F1-270R1 -- N/A
F1-270R2 -- N/A
F1-274 53 N/A
F1-276 22 N/A
F1-277 61 N/A
F1-278 64 N/A
F1-279 21 N/A
F1-279R1 -- N/A
F1-282 31 12 January 1966
F1-283 65 14 October 1966
F1-283R1 -- N/A
F1-283R2 -- N/A
F1-285 68 28 September 1965
F1-285R1 -- N/A
F1-287 31 14 October 1966
F1-288 31 14 October 1966
F1-289 63 N/A
F1-289R1 -- N/A
F1-289R2 -- N/A
F1-294 57 17 May 1965
F1-294R1 -- N/A
F1-294R2 -- N/A
F1-303 54 8 August 1966
F1-303R1 -- N/A
F1-304 67 N/A
F1-304R1 -- N/A
F1-305 73 28 September 1965
F1-305R1 -- N/A
F1-306 66 N/A
F1-306R1 -- N/A
F1-306R2 -- N/A
F1-307 74 N/A
F1-307R1 -- N/A
F1-308 31 N/A
F1-309 77,80,95 8 August 1966
F1-310 78,80,95 8 August 1966
F1-311 31,108 28 September 1965
F1-311R1 -- N/A
F1-312 96,97 12 January 1966
F1-312R1 -- N/A
F1-312R2 -- N/A
F1-312R3 -- N/A
F1-312R4 179 N/A
F1-313 69 28 September 1965
F1-313R1 -- N/A
F1-314 31 28 September 1965
F1-315 70,83 28 September 1965
F1-315R1 -- N/A
F1-315R2 -- N/A
F1-316 31 8 August 1966
F1-317 71 8 August 1966
F1-319 31 N/A
F1-320 75 8 August 1966
F1-320R1 -- N/A
F1-321 31 28 September 1965
F1-323 84,85,86 N/A
F1-323R1 -- N/A
F1-323R2 -- N/A
F1-323R3 -- N/A
F1-324 72 28 September 1965
F1-324R1 -- N/A
F1-326 79,80,95 N/A
F1-328 76 28 September 1965
F1-328R1 -- N/A
F1-331 31 8 August 1966
F1-332 31 N/A
F1-333 54 8 August 1966
F1-335 31 31 March 1967
F1-342 30 N/A
F1-343 90,91 31 March 1967
F1-347 31 31 March 1967
F1-352 31 12 January 1966
F1-352R1 -- N/A
F1-353 82 N/A
F1-356 88,93 28 September 1965
F1-357 89 8 August 1966
F1-358 31 8 August 1966
F1-360 99 8 August 1966
F1-361 92 N/A
F1-362 54 31 March 1967
F1-369 94 8 August 1966
F1-370 106 N/A
F1-370R1 -- N/A
F1-370R2 -- N/A
F1-370R3 -- N/A
F1-370R4 -- N/A
F1-371 31 7 April 1966
F1-372 100 31 March 1967
F1-372R1 -- N/A
F1-372R2 -- N/A
F1-378 58 N/A
F1-378R1 -- N/A
F1-378R2 -- N/A
F1-378R3 -- N/A
F1-379 101 12 January 1966
F1-379R1 -- N/A
F1-379R2 -- N/A
F1-380 99 7 April 1966
F1-381 31 N/A
F1-391 102,103 7 April 1966
F1-391R1 -- N/A
F1-392 137 31 March 1967
F1-392R1 -- N/A
F1-392R2 -- N/A
F1-405 128 31 March 1967
F1-405R1 -- N/A
F1-405R2 -- N/A
F1-406 -- 31 March 1967
F1-407 109 31 March 1967
F1-407R1 -- N/A
F1-408 104 7 April 1966
F1-408R1 -- 7 April 1966
F1-409 105 7 April 1966
F1-410 128 31 March 1967
F1-410R1 -- N/A
F1-415 107 8 August 1966
F1-416 120 31 March 1967
F1-416R1 -- N/A
F1-417 -- N/A
F1-418 -- 31 March 1967
F1-418R1 -- N/A
F1-419 -- 31 March 1967
F1-419R1 -- N/A
F1-420 -- 31 March 1967
F1-420R1 -- N/A
F1-421 -- N/A
F1-421R1 -- N/A
F1-421R2 -- N/A
F1-422 113,114 8 August 1966
F1-422R1 -- N/A
F1-423 119 N/A
F1-423R1 -- N/A
F1-424 110 8 August 1966
F1-424R1 -- N/A
F1-426 117 8 August 1966
F1-426R1 -- N/A
F1-427 111 31 March 1967
F1-427R1 -- N/A
F1-427R2 -- N/A
F1-428 87 N/A
F1-428R1 -- N/A
F1-430 112 8 August 1966
F1-431 137 31 March 1967
F1-431R1 -- N/A
F1-431R2 -- N/A
F1-432 125 31 March 1967
F1-432R1 -- N/A
F1-432R2 -- N/A
F1-434 121 31 March 1967
F1-434R1 -- N/A
F1-436 123 8 August 1966
F1-437 115 14 October 1966
F1-437R1 -- N/A
F1-437R2 -- N/A
F1-437R3 -- N/A
F1-438 131 31 March 1967
F1-439 146 10 August 1967
F1-439R1 -- N/A
F1-441 140 10 August 1967
F1-441R1 -- N/A
F1-441R2 -- N/A
F1-441R3 -- N/A
F1-443 129 14 October 1966
F1-444 139 10 August 1967
F1-444R1 -- N/A
F1-444R2 -- N/A
F1-445 122 8 August 1966
F1-445R1 -- N/A
F1-447 138 N/A
F1-447R1 -- N/A
F1-447R2 -- N/A
F1-448 149 10 August 1967
F1-448R1 -- N/A
F1-448R2 -- N/A
F1-449 127 31 March 1967
F1-449R1 -- N/A
F1-452 126 31 March 1967
F1-452R1 -- N/A
F1-453 123 N/A
F1-454 118 31 March 1967
F1-454R1 -- N/A
F1-454R2 -- N/A
F1-456 124 8 August 1966
F1-456R1 -- N/A
F1-457 136 N/A
F1-459 130 31 March 1967
F1-464 -- 14 October 1966
F1-467 -- N/A
F1-467R1 -- N/A
F1-468 128 31 March 1967
F1-470 140 10 August 1967
F1-470R1 -- N/A
F1-470R2 -- N/A
F1-471 -- N/A
F1-475 -- N/A
F1-475R1 -- N/A
F1-475R2 -- N/A
F1-476 135 31 March 1967
F1-476R1 -- N/A
F1-478 137 N/A
F1-478R1 -- N/A
F1-478R2 -- N/A
F1-480 132 31 March 1967
F1-480R1 -- N/A
F1-482 133,134,142 31 March 1967
F1-482R1 142 10 August 1967
F1-495 144 10 August 1967
F1-495R1 -- N/A
F1-498 145 10 August 1967
F1-498R1 -- N/A
F1-498R2 -- N/A
F1-499 137 10 August 1967
F1-499R1 -- N/A
F1-500 150,151 10 August 1967
F1-500R1 -- N/A
F1-502 148 N/A
F1-504 141 31 March 1967
F1-504R1 141 10 August 1967
F1-505 161 N/A
F1-505R1 -- N/A
F1-505R2 -- N/A
F1-506 159 13 February 1968
F1-507 -- N/A
F1-509 143 N/A
F1-510 152 10 August 1967
F1-510R1 -- N/A
F1-511 146 10 August 1967
F1-511R1 -- N/A
F1-512 177 10 August 1967
F1-512R1 -- N/A
F1-515 147 14 July 1968
F1-515R1 -- N/A
F1-521 154 13 February 1968
F1-521R1 -- N/A
F1-521R2 154 11 March 1968
F1-521R3 -- N/A
F1-521R4 183 N/A
F1-522 -- N/A
F1-523 -- 13 February 1968
F1-524 -- 13 February 1968
F1-525 157,158 13 February 1968
F1-525R1 -- N/A
F1-526 156 14 July 1968
F1-526R1 -- N/A
F1-530 162,163 13 February 1968
F1-530R1 -- N/A
F1-530R2 -- N/A
F1-530R3 -- N/A
F1-535 -- N/A
F1-543 165 11 March 1968
F1-543R1 -- N/A
F1-545 154 11 March 1968
F1-547 169 N/A
F1-548 160 13 February 1968
F1-548R1 -- N/A
F1-552 170 14 July 1968
F1-552R1 -- N/A
F1-552R2 -- N/A
F1-579 -- 11 March 1968
F1-580 -- N/A
F1-581 167,168 14 July 1968
F1-581R1 -- N/A
F1-581R2 -- N/A
F1-581R3 -- N/A
F1-581R4 -- N/A
F1-586 -- N/A
F1-587 -- N/A
F1-590 176 18 August 1969
F1-590R1 -- N/A
F1-590R2 -- N/A
F1-590R3 -- N/A
F1-590R4 -- N/A
F1-591 172 N/A
F1-592 173 18 August 1969
F1-592R1 -- N/A
F1-594 -- N/A
F1-594R1 -- N/A
F1-596 174 N/A
F1-596R1 -- N/A
F1-597 175 N/A
F1-601 -- N/A
F1-602 178 N/A
F1-604 180 4 November 1970
F1-607 181 4 November 1970
F1-607R1 -- N/A
F1-607R2 -- N/A
F1-607R3 -- N/A
F1-612 184,185 4 November 1970
F1-612R1 -- N/A
F1-612R2 -- N/A
F1-613 186,187 4 November 1970
F1-617 -- N/A
F1-618 188,189,190 N/A
F1-618R1 -- N/A

The bulk of the descriptive text was taken, largely verbatim, from F-1 Rocket Engine Technical Manual: Engine Data (R-3896-1).