Narrative:

During rollout on flight X at HA21 am, copilot applied maximum reverse thrust (standard). We received a 3 bell chime but looking at engine instruments appeared normal. Since we saw no visual signs of overspd (normal N2 tape turns red) we did not write it up. Next leg I landed using idle reverse. During next rollout at XB15 pm, as copilot engaged reverse thrust to maximum reverse, I called EPR readings and again we received 3 bell chime but this time N2 on engine #1 tape turned red. Copilot quickly reduced reverse. For maintenance log, I asked copilot what was maximum N2 during overspd since I was looking outside and did not see N2. He said it was 106 percent and I wrote it up accordingly. Several hours later (4), he realized that maximum reverse thrust parameters (red line) moves down to 93 percent during thrust reverse operation. Therefore, we advised maintenance that overspd was only to 96 percent. Maintenance said it did not matter because the same engine overheated to 900 degrees C during ferry flight to pit. Suggestions: we should be using less than maximum reverse thrust (second detent). This puts N2 right at 93 percent which is its maximum. This aircraft had been written up earlier that they could not get reverse level past idle position. Write-up had been cleared and tested. They must not have tested it to the second detent because we had same problem and wrote it up again after above incident.

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Original NASA ASRS Text

Title: AN ACR MLG CREW WROTE UP AN ENG OVERSPD WRONG IN THE LOGBOOK.

Narrative: DURING ROLLOUT ON FLT X AT HA21 AM, COPLT APPLIED MAX REVERSE THRUST (STANDARD). WE RECEIVED A 3 BELL CHIME BUT LOOKING AT ENG INSTS APPEARED NORMAL. SINCE WE SAW NO VISUAL SIGNS OF OVERSPD (NORMAL N2 TAPE TURNS RED) WE DID NOT WRITE IT UP. NEXT LEG I LANDED USING IDLE REVERSE. DURING NEXT ROLLOUT AT XB15 PM, AS COPLT ENGAGED REVERSE THRUST TO MAX REVERSE, I CALLED EPR READINGS AND AGAIN WE RECEIVED 3 BELL CHIME BUT THIS TIME N2 ON ENG #1 TAPE TURNED RED. COPLT QUICKLY REDUCED REVERSE. FOR MAINT LOG, I ASKED COPLT WHAT WAS MAX N2 DURING OVERSPD SINCE I WAS LOOKING OUTSIDE AND DID NOT SEE N2. HE SAID IT WAS 106 PERCENT AND I WROTE IT UP ACCORDINGLY. SEVERAL HRS LATER (4), HE REALIZED THAT MAX REVERSE THRUST PARAMETERS (RED LINE) MOVES DOWN TO 93 PERCENT DURING THRUST REVERSE OP. THEREFORE, WE ADVISED MAINT THAT OVERSPD WAS ONLY TO 96 PERCENT. MAINT SAID IT DID NOT MATTER BECAUSE THE SAME ENG OVERHEATED TO 900 DEGS C DURING FERRY FLT TO PIT. SUGGESTIONS: WE SHOULD BE USING LESS THAN MAX REVERSE THRUST (SECOND DETENT). THIS PUTS N2 RIGHT AT 93 PERCENT WHICH IS ITS MAX. THIS ACFT HAD BEEN WRITTEN UP EARLIER THAT THEY COULD NOT GET REVERSE LEVEL PAST IDLE POS. WRITE-UP HAD BEEN CLRED AND TESTED. THEY MUST NOT HAVE TESTED IT TO THE SECOND DETENT BECAUSE WE HAD SAME PROB AND WROTE IT UP AGAIN AFTER ABOVE INCIDENT.

Data retrieved from NASA's ASRS site as of July 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.