C172 instructor and pilot had split flaps on go around.

Attributes
ACN	474584
Time
Date	200005
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : gai.airport
State Reference	MD
Altitude	agl single value : 600
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : cre.tower
Operator	general aviation : instructional
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	landing : go around
Flight Plan	None
Person 1
Affiliation	other
Function	instruction : instructor
Qualification	pilot : cfi pilot : commercial pilot : multi engine pilot : instrument
Experience	flight time last 90 days : 35 flight time total : 3600 flight time type : 750
ASRS Report	474584
Person 2
Affiliation	other
Function	instruction : trainee
Qualification	pilot : student
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : landed in emergency condition flight crew : declared emergency
Consequence	other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

While completing VOR runway 14 to gai instrument student turned right to enter left base to runway 14. He lowered flaps to 40 degrees and started descending. I advised him he was too high and to go around. He raised flaps (switch up) for go around. There was a 'pop' sound and I said 'what was that' as I scanned right then left. Student said the controls were not right as I saw the left flap fully extended and the right flap up. I told him we had a split flap and I had the airplane. I managed to arrest the right turn and establish a gentle turn to the left with roll control available. A radio call on CTAF to an aircraft on ground was made requesting them to stay by for an emergency landing. A gradual descent was made while in the left turn and the flaps left in their existing condition. Aircraft was landed without problem. Investigation revealed a failed outer track bearing jamming flap in 30-40 degrees down. The retraction system jackscrew had wrapped parts around itself. NTSB and FSDO advised the next morning and FSDO technical representative assisted in the check. Very little of the flap system can be checked on preflts and the needle bearing failed without warning. Aircraft has 9000+ hours (1975 new).

Original NASA ASRS Text

Title: C172 INSTRUCTOR AND PLT HAD SPLIT FLAPS ON GAR.

Narrative: WHILE COMPLETING VOR RWY 14 TO GAI INST STUDENT TURNED R TO ENTER L BASE TO RWY 14. HE LOWERED FLAPS TO 40 DEGS AND STARTED DSNDING. I ADVISED HIM HE WAS TOO HIGH AND TO GO AROUND. HE RAISED FLAPS (SWITCH UP) FOR GAR. THERE WAS A 'POP' SOUND AND I SAID 'WHAT WAS THAT' AS I SCANNED R THEN L. STUDENT SAID THE CTLS WERE NOT RIGHT AS I SAW THE L FLAP FULLY EXTENDED AND THE R FLAP UP. I TOLD HIM WE HAD A SPLIT FLAP AND I HAD THE AIRPLANE. I MANAGED TO ARREST THE R TURN AND ESTABLISH A GENTLE TURN TO THE L WITH ROLL CTL AVAILABLE. A RADIO CALL ON CTAF TO AN ACFT ON GND WAS MADE REQUESTING THEM TO STAY BY FOR AN EMER LNDG. A GRADUAL DSCNT WAS MADE WHILE IN THE L TURN AND THE FLAPS LEFT IN THEIR EXISTING CONDITION. ACFT WAS LANDED WITHOUT PROB. INVESTIGATION REVEALED A FAILED OUTER TRACK BEARING JAMMING FLAP IN 30-40 DEGS DOWN. THE RETRACTION SYS JACKSCREW HAD WRAPPED PARTS AROUND ITSELF. NTSB AND FSDO ADVISED THE NEXT MORNING AND FSDO TECHNICAL REPRESENTATIVE ASSISTED IN THE CHK. VERY LITTLE OF THE FLAP SYS CAN BE CHKED ON PREFLTS AND THE NEEDLE BEARING FAILED WITHOUT WARNING. ACFT HAS 9000+ HRS (1975 NEW).

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.