1、Lessons Learned Entry: 1626Lesson Info:a71 Lesson Number: 1626a71 Lesson Date: 2005-06-30a71 Submitting Organization: DFRCa71 Authored by: Richard WongSubject: X-43A Rudder/Wing Impact Mishap Investigation Lessons Learned Abstract: On the afternoon of June 17, 2004, there was a request to implement
2、an approved Configuration Change Request to increase the left wing-fuselage clearance of the X-43A research vehicle. To accomplish this required some trimming to the left wing leading edge. In order to perform this modification, the avionics technician positioned the left wing leading edge up by hal
3、ting an incomplete ground Built-in-Test (BIT) that allowed access for the work. Power was removed from the vehicle to allow the work to be performed safely. Contractors then completed the modification to the wing. The technician restored power to the vehicle and attempted to lower the wing by repeat
4、ing the surface BIT. The rudder swept into the (still raised) wing causing minor structural damage to the rudder and the wing as the surfaces impacted. The BIT was stopped and power to the vehicle was removed. Description of Driving Event: Late in the afternoon on Thursday, 17 June 2004, while in th
5、e process of performing a small modification to the left wing of the X-43A, the left rudder collided with the left horizontal wing. Visual inspection shows a small dent in the rudder and the wing at the point of impact. In addition to this, there is an offset in the rudder, approximately 3 degrees.
6、On the evening of June 16, the Operations Engineer and the Systems Engineer had discussed planning activities for the X-43 for the following day, which included the possibility of performing the left wing leading edge. Electrical pre-mating activities were to be conducted. If time permitted during t
7、hose activities then the left wing trimming activities would be worked into the schedule. They discussed the process of how they were going to perform the trimming activity. Normal process for moving an individual surface would be via using a break out box and isolate the surface following a set of
8、procedures or checklist. However, due to the integration testing for the electrical pre-mating activities, using a break out box would break the continuity between the research vehicle Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-and the adapter.
9、The Systems Engineer suggested running and stopping the Built-In-Test (BIT) to move the wing into the proper position. The System Engineer stated that he would need to think about how to move the left wing up to perform the trimming work and write up some procedures to move the wing into the proper
10、positions. The Operations Engineer discussed that this activity would be briefed with a Test Readiness Review before performing the activity. On the morning of June 17, at the daily 7:15 a.m. morning meeting, activities were discussed for the days aircraft activities. Most of the activities involved
11、 the integration check out with the electrical pre-mating. The left wing leading edge trimming was also discussed as a possibility if time permitted. The priorities of the day were to finish the electrical pre-mating activities. Electrical pre-mating activities progressed throughout most of the day.
12、 In the early to mid afternoon, there was an informal meeting between the Operations Engineer, Systems Engineer, and others whose identities is unclear due to inconsistent testimonies. The meeting discussed status of the days activities and as a result of it; the decision to postpone the left wing l
13、eading edge trimming until the next day and possibly into the next week to allow ample time to complete the electrical pre-mating activities. Soon thereafter (late afternoon), the ATK contractors requested the assistance of the X-43 Lead Avionics Technician in implementing the modification to the le
14、ft leading edge wing. In order to perform the modification on the left leading edge wing, the wing had to be rotated leading edge up in order to allow access for the trimming. The approval process required to proceed with this activity is unclear due to inconsistent testimonies. There was no Test Re
15、adiness Review or pre-brief prior to this activity. There was no engineering direction to start the work. There was no test conductor conducting the activity nor were there written procedures used. The Avionics Technician positioned the wing by powering up the ship with 28V, followed by 150V, and th
16、en turning on the ground version of the surface built-in-test (BIT). The flight control computer commanded the left rudder to full sweep, returned it to zero, followed by the right rudder, and then the left wing. Once the left wing rotated to the correct position, the BIT was stopped and all power t
17、o the vehicle was turned off. The ATK contractor performed the leading edge trim work and requested that the wing be returned to the zero position. The Avionics Technician proceeded to power up the vehicle 28V, then 150V and then commanded the ground BIT. At this point the flight control computer ze
18、roed the left rudder, commanded to full sweep (inboard then outboard), at which time the rudder surface struck the left wing, which was still at its leading edge up position. Once the left rudder completed its full sweep, the right rudder was commanded through its sweep. The BIT continued and the le
19、ft wing was returned to zero. At that point the Avionics Technician stopped the BIT and turned off all power. The left rudder surface was at a slight inboard position when it should have been at the zero position. Lesson(s) Learned: Develop and follow procedures for non-standard operations of the BI
20、T. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Recommendation(s): 1. Modify the BIT software to prevent surface contact.2. Ensure that the Systems Engineer is actively involved during any control surface movements. If surfaces are not being moved
21、 using an approved method (i.e. breakout box).3. Develop procedures for non-standard operations of the BIT.4. Create a hazard report for the possibility of the surfaces colliding.5. Develop a standard process of communications for scheduling activities.6. The Operations Engineer and Systems Engineer
22、 should be consulted before work is performed on the aircraft.7. Ensure second designated observer (i.e. avionics technician, engineer, crew chief, or contractor) is aware of their responsibility during movement of the control surfaces.8. Provide a way for the BIT operator to see the surfaces while
23、operating the BIT.Refrain from scheduling activities on the Scheduling Board before all supporting procedures are written. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Aeronautics ResearchAdditional Key Phrase(s):
24、 a71 Accident Investigationa71 Aircrafta71 Extra-Vehicular Activitya71 Ground Operationsa71 Human Factorsa71 Research & Developmenta71 Test ArticleAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2006-03-15a71 Approval Name: dkruhma71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
