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2

PAYLOADS 

SYNCOM 

The SYNCOM deployment was completely nominal. Significant observations that may aid crews deploying SYNCOMS in the future are as follows. 

There was an approximate increase of 56 amps in fuel cell current when the SYNCOM heaters were activated during post insertion. No change in the current was observed at cradle heater activation. The requirement to monitor the fuel cell current during heater ops, while easily accomplished, should be readdressed in light of the data obtained on this flight. 

Prior to flight, the duty of cycle of the thermostatically controlled Solar Panel Heaters was unknown. The SSP Solar Panel On talkback was never observed to cycle. It was gray at heater turn-on and remained gray to heater deactivation. 

During the flight the Batt 2 Pack 3 temperature exceeded the checklist limit of 84° F. The limit was raised to 90° F on MCC call with instructions to wave off the deploy if that limit was exceeded. Maximum observed temperature was 86° F. There are no FDA annunciations for any SYNCOM heater temperature limits, no malfunction procedures for an out-of-limit condition, and the last required crew check of temperature is at D-01:15:00. If the temperatures are to be GO/NO-GO criteria up to the moment of deploy, then the appropriate checklist changes and malfunction procedure additions should be made. Additionally, if the crew response is deemed time-critical to an out-of-limit temperature, then the parameter should be FDA-ed. 

Upon pin retraction with A motors, B OUT limit switch closures did not correspond to those seen during IVT. All B OUT limit switches were closed when retraction was continued with the B motors. 

Pin-out drive times varied from a fastest of 4:34 (forward pivot) to a slowest of 5:13 (keel). During pad IVT a problem with inserting the forward pivot pin on motor B was observed. While the exact cause of the problem is unknown at this time, it manifested itself as an intermittent pin drive. During flight a MCC call directed the crew to the stuck pin malfunction procedure if this condition was observed during any pin retraction. This conflicts with the checklist callout to continue pin drive on the selected motor if, after 6 minutes, pin drive is still visible. If this problem remains a possibility on future flights, the checklist should be modified to reflect the desired crew response.

Deployment could be detected by a "thump" in the Orbiter structure. Spacecraft deployment imparted no significant roll rate to the free-drifting Orbiter.

CRT indications of deployment were a simultaneous "-4L" reading for all temperature parameters on Spec 210, indicating both S/C umbilicals pulled simultaneously. 

S/C OMNI antenna deployment was easily visible as was S/C spin-up. The spin-up was detected only by the increase in S/C RPM. The spin-up thruster firings were not visible. As the S/C reached its spin-up RPM, it appeared to have a slight wobble.