Narrative:

A friend asked me to try his savage and give an opinion on the ground handling. Concerns were that the brakes had been changed to a new type and the tailwheel lock/swivel action was unpredictable. First afternoon we taxied it around the ramp area and did a couple of low-speed taxi tests on the runway. My friend (in front seat) had tendency to ride the brakes while thinking his feet were not on them. Back seat they seemed to work ok. Tailwheel lock/unlock action was unpredictable; with the aircraft suddenly non-responsive to steering input while tailwheel was full-swivel. Also; right brake developed a leak at the brake housing input fitting. We stopped testing; so he could get adjustments done; and agreed to go again a few days later. 4 days later; we met in the later afternoon for more taxi testing. Same routine as before. Tailwheel lock/swivel seemed better; no brake fitting leaks. Taxied on the ramp about 30 mins; then went to the runway for low-speed and mid-speed checks. Low-speed with about 3200-3500 RPM (maximum 5800 RPM allowable) showed a twitchy aircraft; but controllable. He still had trouble with riding the brakes; but not as before. I had no problem with the brakes from the back seat. After several runs; we switched seats so I was in the front; to see whether he had the same trouble with the back; or if I had it in the front. I didn't notice any tendency for the brakes to grab or drag when I was in the front. We tried slow-speed checks; results as before; twitchy but controllable. Then I tried a mid-speed test with RPM at 4000. Tail came up with full forward stick; as expected. After getting to about 50 mph; with the stick about halfway forward; the aircraft started to get twitchy. I pulled back the throttle; at which time the tail dropped rapidly even as I applied full forward stick. The tailwheel bounced hard. The aircraft started to drift left off centerline; so I applied full right rudder without apparent effect. I applied full right brake; but it felt like I only got about half the braking action expected. By now we were drifting off the pavement; so I applied both brakes full on; with the rudder full right even though we were below the speed I expected the rudder to still be effective (we were about 30-35 mph). The aircraft's left drift increased; as the left brake caught with full effectiveness. So I relaxed left brake; continued to apply full right rudder and full right brake. When it became apparent we would hit the brush; I applied full brake on both sides hoping the aircraft would ground loop left before going off the edge of the prepared surface. It didn't. When I tied the rope on the tailwheel mounting spring to pull the aircraft back up the embankment on monday evening; I noticed the right tailwheel steering chain was broken. It was wednesday when someone else pointed out the significance of that broken chain. With the aircraft below rudder effectiveness speed; the only way it could be steered to the right was with tailwheel steering which was broken or with brake. I looked at the aircraft again wednesday evening and realized that the front seat brake pedals had contacted a fuselage crosstube while I had pushed as far as possible. I don't believe I had full right brake pressure because the brake travel was restr when I held that rudder pedal fully forward. 3 days after the incident the insurance claims adjuster who examined the aircraft told me my analysis might or might not be correct; but he believes the restr rudder control was caused by a headset packing form which jammed in the right rudder control cable linkage; out of sight behind the aft end of the rear seat. He found it while looking forward; inside the aft fuselage; through the ripped fabric fuselage covering. We did not see the obstruction from the cockpit. It had been stowed in the baggage bin on jun/xa/07; but the bin was left unzipped and we did all our taxi testing with the cockpit swing-up door open; since there was no intent for flight. I think the adjuster is right. The packing form blew out of the bin; lodged unseen under the seat; and jammed the controls. Anything else which mighthave happened was incidental.

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Original NASA ASRS Text

Title: HOMEBUILT SMA DEPARTS RWY DURING HIGH SPEED TAXI TESTS OF FAULTY BRAKE SYSTEM.

Narrative: A FRIEND ASKED ME TO TRY HIS SAVAGE AND GIVE AN OPINION ON THE GND HANDLING. CONCERNS WERE THAT THE BRAKES HAD BEEN CHANGED TO A NEW TYPE AND THE TAILWHEEL LOCK/SWIVEL ACTION WAS UNPREDICTABLE. FIRST AFTERNOON WE TAXIED IT AROUND THE RAMP AREA AND DID A COUPLE OF LOW-SPD TAXI TESTS ON THE RWY. MY FRIEND (IN FRONT SEAT) HAD TENDENCY TO RIDE THE BRAKES WHILE THINKING HIS FEET WERE NOT ON THEM. BACK SEAT THEY SEEMED TO WORK OK. TAILWHEEL LOCK/UNLOCK ACTION WAS UNPREDICTABLE; WITH THE ACFT SUDDENLY NON-RESPONSIVE TO STEERING INPUT WHILE TAILWHEEL WAS FULL-SWIVEL. ALSO; R BRAKE DEVELOPED A LEAK AT THE BRAKE HOUSING INPUT FITTING. WE STOPPED TESTING; SO HE COULD GET ADJUSTMENTS DONE; AND AGREED TO GO AGAIN A FEW DAYS LATER. 4 DAYS LATER; WE MET IN THE LATER AFTERNOON FOR MORE TAXI TESTING. SAME ROUTINE AS BEFORE. TAILWHEEL LOCK/SWIVEL SEEMED BETTER; NO BRAKE FITTING LEAKS. TAXIED ON THE RAMP ABOUT 30 MINS; THEN WENT TO THE RWY FOR LOW-SPD AND MID-SPD CHKS. LOW-SPD WITH ABOUT 3200-3500 RPM (MAX 5800 RPM ALLOWABLE) SHOWED A TWITCHY ACFT; BUT CONTROLLABLE. HE STILL HAD TROUBLE WITH RIDING THE BRAKES; BUT NOT AS BEFORE. I HAD NO PROB WITH THE BRAKES FROM THE BACK SEAT. AFTER SEVERAL RUNS; WE SWITCHED SEATS SO I WAS IN THE FRONT; TO SEE WHETHER HE HAD THE SAME TROUBLE WITH THE BACK; OR IF I HAD IT IN THE FRONT. I DIDN'T NOTICE ANY TENDENCY FOR THE BRAKES TO GRAB OR DRAG WHEN I WAS IN THE FRONT. WE TRIED SLOW-SPD CHKS; RESULTS AS BEFORE; TWITCHY BUT CONTROLLABLE. THEN I TRIED A MID-SPD TEST WITH RPM AT 4000. TAIL CAME UP WITH FULL FORWARD STICK; AS EXPECTED. AFTER GETTING TO ABOUT 50 MPH; WITH THE STICK ABOUT HALFWAY FORWARD; THE ACFT STARTED TO GET TWITCHY. I PULLED BACK THE THROTTLE; AT WHICH TIME THE TAIL DROPPED RAPIDLY EVEN AS I APPLIED FULL FORWARD STICK. THE TAILWHEEL BOUNCED HARD. THE ACFT STARTED TO DRIFT L OFF CTRLINE; SO I APPLIED FULL R RUDDER WITHOUT APPARENT EFFECT. I APPLIED FULL R BRAKE; BUT IT FELT LIKE I ONLY GOT ABOUT HALF THE BRAKING ACTION EXPECTED. BY NOW WE WERE DRIFTING OFF THE PAVEMENT; SO I APPLIED BOTH BRAKES FULL ON; WITH THE RUDDER FULL R EVEN THOUGH WE WERE BELOW THE SPD I EXPECTED THE RUDDER TO STILL BE EFFECTIVE (WE WERE ABOUT 30-35 MPH). THE ACFT'S L DRIFT INCREASED; AS THE L BRAKE CAUGHT WITH FULL EFFECTIVENESS. SO I RELAXED L BRAKE; CONTINUED TO APPLY FULL R RUDDER AND FULL R BRAKE. WHEN IT BECAME APPARENT WE WOULD HIT THE BRUSH; I APPLIED FULL BRAKE ON BOTH SIDES HOPING THE ACFT WOULD GND LOOP L BEFORE GOING OFF THE EDGE OF THE PREPARED SURFACE. IT DIDN'T. WHEN I TIED THE ROPE ON THE TAILWHEEL MOUNTING SPRING TO PULL THE ACFT BACK UP THE EMBANKMENT ON MONDAY EVENING; I NOTICED THE R TAILWHEEL STEERING CHAIN WAS BROKEN. IT WAS WEDNESDAY WHEN SOMEONE ELSE POINTED OUT THE SIGNIFICANCE OF THAT BROKEN CHAIN. WITH THE ACFT BELOW RUDDER EFFECTIVENESS SPD; THE ONLY WAY IT COULD BE STEERED TO THE R WAS WITH TAILWHEEL STEERING WHICH WAS BROKEN OR WITH BRAKE. I LOOKED AT THE ACFT AGAIN WEDNESDAY EVENING AND REALIZED THAT THE FRONT SEAT BRAKE PEDALS HAD CONTACTED A FUSELAGE CROSSTUBE WHILE I HAD PUSHED AS FAR AS POSSIBLE. I DON'T BELIEVE I HAD FULL R BRAKE PRESSURE BECAUSE THE BRAKE TRAVEL WAS RESTR WHEN I HELD THAT RUDDER PEDAL FULLY FORWARD. 3 DAYS AFTER THE INCIDENT THE INSURANCE CLAIMS ADJUSTER WHO EXAMINED THE ACFT TOLD ME MY ANALYSIS MIGHT OR MIGHT NOT BE CORRECT; BUT HE BELIEVES THE RESTR RUDDER CTL WAS CAUSED BY A HEADSET PACKING FORM WHICH JAMMED IN THE R RUDDER CTL CABLE LINKAGE; OUT OF SIGHT BEHIND THE AFT END OF THE REAR SEAT. HE FOUND IT WHILE LOOKING FORWARD; INSIDE THE AFT FUSELAGE; THROUGH THE RIPPED FABRIC FUSELAGE COVERING. WE DID NOT SEE THE OBSTRUCTION FROM THE COCKPIT. IT HAD BEEN STOWED IN THE BAGGAGE BIN ON JUN/XA/07; BUT THE BIN WAS LEFT UNZIPPED AND WE DID ALL OUR TAXI TESTING WITH THE COCKPIT SWING-UP DOOR OPEN; SINCE THERE WAS NO INTENT FOR FLT. I THINK THE ADJUSTER IS RIGHT. THE PACKING FORM BLEW OUT OF THE BIN; LODGED UNSEEN UNDER THE SEAT; AND JAMMED THE CTLS. ANYTHING ELSE WHICH MIGHTHAVE HAPPENED WAS INCIDENTAL.

Data retrieved from NASA's ASRS site as of January 2009 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.