1、Lessons Learned Entry: 0628Lesson Info:a71 Lesson Number: 0628a71 Lesson Date: 1999-07-20a71 Submitting Organization: ARCa71 Submitted by: Dave ZimmerSubject: Fan Screen Placement Considerations for Space Flight Applications Description of Driving Event: During the STS-90 flight, two of the internal
2、 air circulation fans within the Research Animal Holding Facility (RAHF) failed to operate. To successfully complete the mission, an in-flight procedure was utilized to maintain the required air flow. Upon landing and recovery, an investigation was conducted to determine the cause of the failed fans
3、A small (approximately 6.0 X 0.5 X 0.1 inch) cloth/velcro strap was found to have been ingested into the RAHF air flow, and was eventually pinched between the fan blade and the rotor housing causing the fan to stop. The cloth strap came loose from another piece of stowage hardware and was apparentl
4、y ingested into the RAHF through an opening while one of the removable rodent habitats was being removed or replaced. While the RAHF has an inlet filter over the main air inlet to the unit (that would have stopped this strap), it does not have a filter directly in front of the circulation fans that
5、would catch any debris in the system, regardless of source.Lesson(s) Learned: While it is important to have air filters on the air-inlet to space flight hardware (to facilitate cleaning), it is equally important to have a filter directly in front of any internal fan blades to protect the fans from d
6、ebris (regardless of source) during in-flight operations. Not only will this protect the fans from debris caused by external sources, but it will allow the fans to remain operational if any of the internal components become loose (or float free) during the launch.Recommendation(s): Place a filter di
7、rectly in front of all fans used in space flight operations.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71
8、 Aeronautics ResearchAdditional Key Phrase(s): a71 Flight Equipmenta71 Hardwarea71 Payloadsa71 Research & Developmenta71 Safety & Mission Assurancea71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1999-08-02a71 Approval Name: Anthony Bricenoa71 Approval Organization: N244-30a71 Approval Phone Number: 415-604-1012Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
