ACR WDB EXPERIENCES NOISE AND VIBRATION IN DSCNT AT HIGH SPD IN A NIGHT OP.

Narrative

DSNDING AT 320 KIAS THROUGH FL190 INTO ORD; EXPERIENCED A LOUD AURAL RPT AND A SHARP JOLT; ACCOMPANIED BY THE ONSET OF MODERATE AIR FRAME BUFFETING AND UNUSUAL LOUD AIRSTREAM NOISES. BEGAN AN IMMEDIATE SPD REDUCTION TO JUST ABOVE CLEAN MANEUVERING SPD AND AFTER A VISUAL INSPECTION DISCLOSED NO OBVIOUS DAMAGE TO THE SLATS; WINGS AND FLAPS. SLOWED FURTHER TO FLAP 15 DEGS MANEUVERING SPD (170 KIAS). THE SPD REDUCTIONS MODERATED THE BUFFETING AND NOISE CONSIDERABLY. SUSPECTED A FAILED RADOME OR NOSE GEAR DOOR. LOWERED THE GEAR AT THIS POINT AND RECEIVED NORMAL INDICATIONS; WITH A FURTHER NOTICEABLE REDUCTION OF BUFFETING AND NOISE. ELECTED TO LEAVE THE GEAR DOWN AND PROCEEDED TO ORD FOR A NORMAL LNDG AND ROLLOUT. AFTER ARRIVING AT THE GATE; MAINT ADVISED THAT THE R NOSE GEAR DOOR WAS HANGING OPEN; AND THAT ITS ACTUATING LINKAGE HAD FAILED. THE ASPECT OF THIS INCIDENT THAT I MUST COMMENT ON IS HOW DISTRACTING AND POTENTIALLY DISORIENTING A LARGE SUDDEN CHANGE IN THE NOISE LEVELS AND FEEL OF THE ACFT CAN BE. WHEN THESE LARGE SUDDEN CHANGES OCCUR; THE CREW CAN BE MOMENTARILY IMMOBILIZED BY A 'STARTLED' REACTION. AS ALWAYS THOUGH; THE NOISE LEVELS AND ACFT FEEL ARE ONLY ONE SET OF CLUES. THE REAL ANSWERS WILL BE FOUND ON THE PANELS IN FRONT OF US. IN THIS CASE WE HAD NO DRASTIC CHANGES IN AIRSPD OR ATTITUDE; AND EVEN THOUGH IT SOUNDED AND FELT VERY DIFFERENT AND FOREIGN; THE ACFT WAS TOTALLY CTLABLE.