|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||0601 To 1200|
|Locale Reference||airport : zzz.airport|
|Altitude||msl single value : 20000|
|Controlling Facilities||tracon : mia.tracon|
|Operator||common carrier : air carrier|
|Make Model Name||B737 Undifferentiated or Other Model|
|Operating Under FAR Part||Part 121|
|Navigation In Use||other|
|Flight Phase||descent : approach|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Qualification||pilot : atp|
|Affiliation||company : air carrier|
|Function||flight crew : first officer|
|Anomaly||aircraft equipment problem : critical|
other anomaly other
|Independent Detector||other flight crewa|
other flight crewb
|Resolutory Action||none taken : detected after the fact|
Chart Or Publication
I flew from ZZZZ to ZZZ departing at XA50. Tail section and wings were de-iced and I called dispatch to advise and got new paperwork with 270 KT restriction. ZZZZ maintenance put entry into logbook along with sticker in cockpit noting maximum speed 270 KIAS. On taxi out, I made sure the first officer cycled the elevator flight controls 3 times as per operations procedure. Cruise portion went without a hitch. During descent into ZZZ at approximately FL200, with autoplt on and speed brakes deployed, we felt a large 'jolt like' bump from the elevator section of the airplane. It was not wake turbulence. No one was ahead of us and it didn't feel like any wake I've ever encountered before. It felt as if someone had 'punched' the control yoke forward one time. Our airspeed was about 260 KTS at this time. I did not get a look at outside air temperature. This jolt really got our attention in light of the elevator de-icing problems the B737 has. Callback conversation with reporter revealed the following information: the reporter stated the maintenance action taken on the logbook report is unknown. The reporter said the jolt and elevator movement may be associated with the deicing problem on the B737-800. The reporter said when the B737-800 is deiced a speed restriction of 270 knots is placed on the airplane, a preflight check is required of the elevator on taxi out to three movements up and down. The reporter stated the speed restriction can only be lifted after maintenance makes two required inspections and clears the logbook. The reporter said the components or elevator configuration causing these restrictions in unknown.
Original NASA ASRS Text
Title: A B737-800 IN DSCNT AT FL200 EXPERIENCED A LARGE ELEVATOR 'JOLT LIKE' BUMP FROM THE ELEVATOR SECTION. RPTR BELIEVES PROB ASSOCIATED WITH ELEVATOR DEICING PROBLEM.
Narrative: I FLEW FROM ZZZZ TO ZZZ DEPARTING AT XA50. TAIL SECTION AND WINGS WERE DE-ICED AND I CALLED DISPATCH TO ADVISE AND GOT NEW PAPERWORK WITH 270 KT RESTRICTION. ZZZZ MAINT PUT ENTRY INTO LOGBOOK ALONG WITH STICKER IN COCKPIT NOTING MAX SPEED 270 KIAS. ON TAXI OUT, I MADE SURE THE FO CYCLED THE ELEVATOR FLT CTLS 3 TIMES AS PER OPS PROCEDURE. CRUISE PORTION WENT WITHOUT A HITCH. DURING DSCNT INTO ZZZ AT APPROX FL200, WITH AUTOPLT ON AND SPEED BRAKES DEPLOYED, WE FELT A LARGE 'JOLT LIKE' BUMP FROM THE ELEVATOR SECTION OF THE AIRPLANE. IT WAS NOT WAKE TURBULENCE. NO ONE WAS AHEAD OF US AND IT DIDN'T FEEL LIKE ANY WAKE I'VE EVER ENCOUNTERED BEFORE. IT FELT AS IF SOMEONE HAD 'PUNCHED' THE CTL YOKE FORWARD ONE TIME. OUR AIRSPEED WAS ABOUT 260 KTS AT THIS TIME. I DID NOT GET A LOOK AT OUTSIDE AIR TEMP. THIS JOLT REALLY GOT OUR ATTENTION IN LIGHT OF THE ELEVATOR DE-ICING PROBLEMS THE B737 HAS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE MAINT ACTION TAKEN ON THE LOGBOOK RPT IS UNKNOWN. THE RPTR SAID THE JOLT AND ELEVATOR MOVEMENT MAY BE ASSOCIATED WITH THE DEICING PROB ON THE B737-800. THE RPTR SAID WHEN THE B737-800 IS DEICED A SPEED RESTRICTION OF 270 KNOTS IS PLACED ON THE AIRPLANE, A PREFLT CHECK IS REQUIRED OF THE ELEVATOR ON TAXI OUT TO THREE MOVEMENTS UP AND DOWN. THE RPTR STATED THE SPEED RESTRICTION CAN ONLY BE LIFTED AFTER MAINT MAKES TWO REQUIRED INSPECTIONS AND CLEARS THE LOGBOOK. THE RPTR SAID THE COMPONENTS OR ELEVATOR CONFIGURATION CAUSING THESE RESTRICTIONS IN UNKNOWN.
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.