NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Due to the lapse in federal government funding, NASA is not updating this website. We sincerely regret this inconvenience.

Back to Results
Independent Orbiter Assessment (IOA): Analysis of the elevon subsystemThe results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are 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. This report documents the independent analysis results for the Orbiter Elevon system hardware. The elevon actuators are located at the trailing edge of the wing surface. The proper function of the elevons is essential during the dynamic flight phases of ascent and entry. In the ascent phase of flight, the elevons are used for relieving high wing loads. For entry, the elevons are used to pitch and roll the vehicle. Specifically, the elevon system hardware comprises the following components: flow cutoff valve; switching valve; electro-hydraulic (EH) servoactuator; secondary delta pressure transducer; bypass valve; power valve; power valve check valve; primary actuator; primary delta pressure transducer; and primary actuator position transducer. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 25 failure modes analyzed, 18 were determined to be PCIs.
Document ID
19900001619
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Wilson, R. E.
(McDonnell-Douglas Corp. Houston, TX, United States)
Riccio, J. R.
(McDonnell-Douglas Corp. Houston, TX, United States)
Date Acquired
September 6, 2013
Publication Date
November 21, 1986
Subject Category
Space Transportation
Report/Patent Number
NAS 1.26:185576
REPT-1.0-WP-VA86001-07
NASA-CR-185576
Report Number: NAS 1.26:185576
Report Number: REPT-1.0-WP-VA86001-07
Report Number: NASA-CR-185576
Accession Number
90N10935
Funding Number(s)
CONTRACT_GRANT: NAS9-17650
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available