Certain diodes - intended to prevent propagation of a single-point failure into redundant circuitry - had been omitted from the flight unit. The diodes appeared on MCP schematics but had been omitted from the hardware because of problems in ground testing. A fix appeared mandatory before flight. The MCP unit in spacecraft 020 would be similarly modified before final integrated tests, to confirm that the design change had not introduced other problems.
Shea requested a full explanation from North American "as to how the schematics and/or drawings being used by the responsible design review engineers did not reflect the as built conditions." A report detailing the loopholes in North American procedures that permitted such a condition and the corrective actions taken to prevent such incidents in the future was requested no later than March 1.