Page 35

These entries are from exactly one year before the start of the Apollo 11 terminal countdown (14 July 1969 2100 GMT).

The team is troubleshooting an issue with a warning light in the radar altimeter display (which would be used to show the LM's height above the surface of the Moon). This display is pictured below in an image from the LEM Guidance, Navigation, and Control Subsystem Study Guide, March 1966 (pdf), which also includes some good control, interface, and configuration diagrams related to the log details.


Radar altimeter display

Grumman Aircraft Engineering Corporation


Page No 73084


A. Rabinowitz






7:48 AM-




LDG RDR received a TDR (TDR #18) due to flickering of a warning light located in ALT/ALT RD meter (9M9) on Panel 1. Occurred during running of OCP-GF-62000-1-RAD-LM5 DEQ 22-035-02 at approx 12:30. Attempted to trace light with no success. Advise contacting following tomorrow.

Harold Weber - LM6
Pat Wiley - Ldg Rdv Subsystem
Frank Kaplan - LM4

S. Sarbello – Night Shift 7/14-15/68

1. EPS support of LDG radar OCP. No new problems occurred related to EPS/lighting.

2. RDR's RDR #18 researched further – level 3 DWGs and LM-5 EFD's show 9M9 as a "black box" (only shows integral & numeric input points). This warning light is not part of the PFI family of lights – however, it's function purpose is similar. This meter has built in logic which requires sensing the presence of AC, DC and radar pulse train to keep the warning light OFF. The OCP attempted to put the light ON by removing the LDG RDR pulse train. The result was a flickering action. Rabinowitz heard this same problem existed in LM-3. Lighting test set OK – suspect random pulses as a possible cause of flicker.

3. LDG RDR OCP completed 06 0715 7/15/68.

E. Dowse 7-15-68

Wrote continuation sheets for TDR's # 12 & 13 which are to be run sequentially when a window is obtained from the STE. The current for this period is not to exceed ten amps and all trouble shooting or satellites should be in standby.

Get 063 to write a PIRR on INV 1 use a TDR #1 continuation sheet to remove the VMIP.
Record PIRR # E 1860

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