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Independent Orbiter Assessment (IOA): Analysis of the guidance, navigation, and control subsystemThe results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) is presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Guidance, Navigation, and Control (GNC) Subsystem hardware are documented. The function of the GNC hardware is to respond to guidance, navigation, and control software commands to effect vehicle control and to provide sensor and controller data to GNC software. Some of the GNC hardware for which failure modes analysis was performed includes: hand controllers; Rudder Pedal Transducer Assembly (RPTA); Speed Brake Thrust Controller (SBTC); Inertial Measurement Unit (IMU); Star Tracker (ST); Crew Optical Alignment Site (COAS); Air Data Transducer Assembly (ADTA); Rate Gyro Assemblies; Accelerometer Assembly (AA); Aerosurface Servo Amplifier (ASA); and Ascent Thrust Vector Control (ATVC). The IOA analysis process utilized available GNC hardware drawings, workbooks, specifications, schematics, and systems briefs for defining hardware assemblies, components, and circuits. Each hardware item was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.
Document ID
19900001604
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Trahan, W. H. (McDonnell-Douglas Astronautics Co. Houston, TX, United States)
Odonnell, R. A. (McDonnell-Douglas Astronautics Co. Houston, TX, United States)
Pietz, K. C. (McDonnell-Douglas Astronautics Co. Houston, TX, United States)
Hiott, J. M. (McDonnell-Douglas Astronautics Co. Houston, TX, United States)
Date Acquired
September 6, 2013
Publication Date
December 19, 1986
Subject Category
Space Transportation
Report/Patent Number
REPT-1.0-WP-VA86001-16
NASA-CR-185555
NAS 1.26:185555
Accession Number
90N10920
Funding Number(s)
CONTRACT_GRANT: NAS9-17650
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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