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2. Orbiter Hardware

• Tires- Loaded heavily during derotation and crosswinds. Fragile enough that KSC centerline lights have been removed. Tire blew out on STS 51-D after only a 30-foot skid at end of rollout. Nosewheel tires may blow at slapdown or show unexpected crosswind wear. 

• Brakes- Energy limited (i.e. not sufficient capacity for steering). Complex crew procedures. Numerous failures. 

•Nosewheel steering - Single string system with numerous single point failures. Development sensitive to the tire model. 

3. Runway and Runway Environment - Runway surface is rough to prevent skids so is hard on tires. Runway is surrounded by a moat -- does not meet United States Air Force (USAF) runway standards. In energy tolerance, the EAFB lakebed complex provides more latitude for energy deviations. Runway orientation (cross runway desired). 

4. Perceived Schedule Pressures - There has been no time allotted for transport after an EAFB landing. 

5. Training - Bird hazard during STA flying
            - no high fidelity training available for landing and rollout.



VI. ISSUE OVERVIEW

The issues brought out by the crew concerns and additionally through this review are summarized in table 1. Each issue is described briefly and the system counter response is given. The remainder of this report further addresses each of these areas. 

If the NSTS Program were to commit to routine landings at EAFB, the program would have several concerns associated with cost, risk, and schedule. These items are summarized in table 2 and include appropriate counter responses. 



VII. FLIGHT RULES 

The end-of-mission landing rules deal with Orbiter systems failures and weather criteria. Systems failures which remove a single level of redundancy from the flight control systems will always call for a lakebed landing (EAFB or WSMR). 

The MCC at NASA Johnson Space Center (JSC) is responsible for determining the end-of-mission landing site and also for determining its go/no go status for entry. The Flight Rules define weather guidelines used in conjunction with forecasts and STA pilot observations. The Flight Rules also specify limits or placards to account for landing deceleration systems limitations. Whenever possible, the STA

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