An air carrier medium large transport flight crew gets a slat disagreement light and finds that the ...

Narrative:

Started a visual approach to runway 23L and extended slats and flaps with autoplt engaged. Observed slat disagreement light on and blue slat extended light did not illuminate. Also got windshear light with no aural warning or aircraft pitch change. Received stall shaker intermittently at higher than expected airspeed. Executed a go around and proceeded west of the airfield to analyze the problem. Requested to remain VFR at 3500 ft MSL. We verified abnormal slat deployment while I hand flew the aircraft and the captain reviewed the company abnormal procedures. When flaps were extended the aircraft started a roll to the left. We selected flaps only (no slats) for approach and landing. After landing was complete and we cleared the runway we terminated the emergency and released the fire trucks. While the situation was resolved with no complications several factors limited crew reaction and resolution time. Fuel was only enough to fly to and land at destination. We considered landing where maintenance was available, but were limited to landing only at destination. No discrete company frequency was available to advise dispatch, or talk with maintenance personnel. Maintenance available at tys was not immediately available and had to be called out after the situation was resolved. Callback conversation with reporter revealed the following information: this first officer of a DC9-30 said that the airport was surrounded by thunderstorms while they were making their approach. The first that they knew of their slat problem was when the slat disagreement light illuminated. They also noted that the 'blue' slat extend light was not on. As the first officer started to troubleshoot the slat problem the captain took the aircraft and started a turn toward runway 23L. The windshear alarm light illuminated, but without an aural warning. This was later determined to have been caused by a slight slip that resulted from the uneven slat deployment. As the captain was rolling out of the turn and starting to slow, the stall warning activated and the flight crew decided to go around. As the flight crew was performing the go around they discovered that the stall warning would activate at speeds as high as 210 KIAS, much higher than anticipated for this confign. They then had the first officer fly the aircraft while they retracted and then extended the flaps and slats, and the first officer noted that there was a pronounced rolling moment which was not present during the initial extension. They then proceeded with the alternate, trailing edge flap extension by use of the split flap/slat handle on the center aisle stand. This was successful and the first officer continued the approach at normal approach +25 KTS, while the captain monitored the aircraft. The reporter said that just as he was flaring to touchdown a large gust hit the aircraft and the tower called reporting at 25 KT tailwind. The reporter said that he touched down at that time as the airspeed dropped from the effect of the tailwind gust. The touchdown and rollout was normal. Maintenance determined later that a slat actuator had failed and they replaced it.

Original NASA ASRS Text

Title: AN ACR MLG FLC GETS A SLAT DISAGREEMENT LIGHT AND FINDS THAT THE SLATS, IN FACT, DID NOT EXTEND TOGETHER AND A ROLLING MOMENT DEVELOPED. AFTER A PERIOD OF ANALYSIS, A NO-SLAT, TRAILING EDGE FLAP ONLY LNDG WAS SAFELY MADE AT VREF +25 KTS.

Narrative: STARTED A VISUAL APCH TO RWY 23L AND EXTENDED SLATS AND FLAPS WITH AUTOPLT ENGAGED. OBSERVED SLAT DISAGREEMENT LIGHT ON AND BLUE SLAT EXTENDED LIGHT DID NOT ILLUMINATE. ALSO GOT WINDSHEAR LIGHT WITH NO AURAL WARNING OR ACFT PITCH CHANGE. RECEIVED STALL SHAKER INTERMITTENTLY AT HIGHER THAN EXPECTED AIRSPD. EXECUTED A GAR AND PROCEEDED W OF THE AIRFIELD TO ANALYZE THE PROB. REQUESTED TO REMAIN VFR AT 3500 FT MSL. WE VERIFIED ABNORMAL SLAT DEPLOYMENT WHILE I HAND FLEW THE ACFT AND THE CAPT REVIEWED THE COMPANY ABNORMAL PROCS. WHEN FLAPS WERE EXTENDED THE ACFT STARTED A ROLL TO THE L. WE SELECTED FLAPS ONLY (NO SLATS) FOR APCH AND LNDG. AFTER LNDG WAS COMPLETE AND WE CLRED THE RWY WE TERMINATED THE EMER AND RELEASED THE FIRE TRUCKS. WHILE THE SIT WAS RESOLVED WITH NO COMPLICATIONS SEVERAL FACTORS LIMITED CREW REACTION AND RESOLUTION TIME. FUEL WAS ONLY ENOUGH TO FLY TO AND LAND AT DEST. WE CONSIDERED LNDG WHERE MAINT WAS AVAILABLE, BUT WERE LIMITED TO LNDG ONLY AT DEST. NO DISCRETE COMPANY FREQ WAS AVAILABLE TO ADVISE DISPATCH, OR TALK WITH MAINT PERSONNEL. MAINT AVAILABLE AT TYS WAS NOT IMMEDIATELY AVAILABLE AND HAD TO BE CALLED OUT AFTER THE SIT WAS RESOLVED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS FO OF A DC9-30 SAID THAT THE ARPT WAS SURROUNDED BY TSTMS WHILE THEY WERE MAKING THEIR APCH. THE FIRST THAT THEY KNEW OF THEIR SLAT PROB WAS WHEN THE SLAT DISAGREEMENT LIGHT ILLUMINATED. THEY ALSO NOTED THAT THE 'BLUE' SLAT EXTEND LIGHT WAS NOT ON. AS THE FO STARTED TO TROUBLESHOOT THE SLAT PROB THE CAPT TOOK THE ACFT AND STARTED A TURN TOWARD RWY 23L. THE WINDSHEAR ALARM LIGHT ILLUMINATED, BUT WITHOUT AN AURAL WARNING. THIS WAS LATER DETERMINED TO HAVE BEEN CAUSED BY A SLIGHT SLIP THAT RESULTED FROM THE UNEVEN SLAT DEPLOYMENT. AS THE CAPT WAS ROLLING OUT OF THE TURN AND STARTING TO SLOW, THE STALL WARNING ACTIVATED AND THE FLC DECIDED TO GAR. AS THE FLC WAS PERFORMING THE GAR THEY DISCOVERED THAT THE STALL WARNING WOULD ACTIVATE AT SPDS AS HIGH AS 210 KIAS, MUCH HIGHER THAN ANTICIPATED FOR THIS CONFIGN. THEY THEN HAD THE FO FLY THE ACFT WHILE THEY RETRACTED AND THEN EXTENDED THE FLAPS AND SLATS, AND THE FO NOTED THAT THERE WAS A PRONOUNCED ROLLING MOMENT WHICH WAS NOT PRESENT DURING THE INITIAL EXTENSION. THEY THEN PROCEEDED WITH THE ALTERNATE, TRAILING EDGE FLAP EXTENSION BY USE OF THE SPLIT FLAP/SLAT HANDLE ON THE CTR AISLE STAND. THIS WAS SUCCESSFUL AND THE FO CONTINUED THE APCH AT NORMAL APCH +25 KTS, WHILE THE CAPT MONITORED THE ACFT. THE RPTR SAID THAT JUST AS HE WAS FLARING TO TOUCHDOWN A LARGE GUST HIT THE ACFT AND THE TWR CALLED RPTING AT 25 KT TAILWIND. THE RPTR SAID THAT HE TOUCHED DOWN AT THAT TIME AS THE AIRSPD DROPPED FROM THE EFFECT OF THE TAILWIND GUST. THE TOUCHDOWN AND ROLLOUT WAS NORMAL. MAINT DETERMINED LATER THAT A SLAT ACTUATOR HAD FAILED AND THEY REPLACED IT.

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.

Attributes
ACN	366596
Time
Date	199704
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : tys
State Reference	TN
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : tys tower : tys tower : chs
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	descent : approach landing other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 8000 flight time type : 1500
ASRS Report	366596
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

An air carrier medium large transport flight crew gets a slat disagreement light and finds that the slats, in fact, did not extend together and a rolling moment developed. After a period of analysis, a no-slat, trailing edge flap only landing was safely made at vref +25 KTS.