Narrative:

While running before takeoff checklist we found that the speed brakes would not arm. After several tries I pulled the speed brake handle back and stowed it several times in the flight position. After the second cycle the brakes automatically engaged making a sudden stop of the aircraft. Fortunately we were moving less than 5 or 6 mph. I discovered this all happened because the automatic brakes were armed as per checklist and the microswitches behind the speed brake handle had been stuck and decided to free up on the second cycle. The equipment then worked normally, so I decided to proceed with the flight since I knew what the trouble was and had been corrected. Lesson learned. If you're going to trouble shoot, stop! Consider all related equipment responses, then check out the equipment.

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Original NASA ASRS Text

Title: ACR MLG MINOR ACFT EQUIPMENT PROBLEM DISCOVERED WHILE RUNNING PRETKOF CHECKLIST. WHEN TROUBLE SHOOTING THE PROBLEM THE AUTOBRAKES CAUSED A SUDDEN STOP FROM A SLOW SPEED. NO INJURIES.

Narrative: WHILE RUNNING BEFORE TKOF CHKLIST WE FOUND THAT THE SPD BRAKES WOULD NOT ARM. AFTER SEVERAL TRIES I PULLED THE SPD BRAKE HANDLE BACK AND STOWED IT SEVERAL TIMES IN THE FLT POS. AFTER THE SECOND CYCLE THE BRAKES AUTOMATICALLY ENGAGED MAKING A SUDDEN STOP OF THE ACFT. FORTUNATELY WE WERE MOVING LESS THAN 5 OR 6 MPH. I DISCOVERED THIS ALL HAPPENED BECAUSE THE AUTO BRAKES WERE ARMED AS PER CHKLIST AND THE MICROSWITCHES BEHIND THE SPD BRAKE HANDLE HAD BEEN STUCK AND DECIDED TO FREE UP ON THE SECOND CYCLE. THE EQUIP THEN WORKED NORMALLY, SO I DECIDED TO PROCEED WITH THE FLT SINCE I KNEW WHAT THE TROUBLE WAS AND HAD BEEN CORRECTED. LESSON LEARNED. IF YOU'RE GOING TO TROUBLE SHOOT, STOP! CONSIDER ALL RELATED EQUIP RESPONSES, THEN CHK OUT THE EQUIP.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.