Narrative:

At cruise FL350 with no speed or confign changes, observed 'leading edge asymmetry' EICAS message and 'leading edge' caution light. No secondary indications were observed. This included a visual inspection, and taking the physical control of the aircraft with the autoplt off. The emergency procedure is written for a confign change situation. There is a caution to maintain 240 KIAS or less in the procedure due to leading edge limitations. I leaned towards maintaining this speed or less, as we didn't know the full extent of the problem and the operating manual is not very descriptive of mechanical protection devices, design, etc. The captain felt that it was an indication problem, and believed that there was little danger of aggravating the situation. Upon arrival at ord we advised approach of higher approach speeds, and the need for an extended final. When configuring for landing and electrically extending trailing edge flaps, received a 'leading edge slat disagree' light. This is normal for the asymmetry situation, but it is not noted in the procedure. While we had reviewed the operating manual, and system knowledge should've precluded any confusion here, it was definitely a distraction to review another extensive emergency procedure, to ensure that nothing in it applied. At the completion of the flight, the captain was unaware of the requirement to pull the cockpit voice recorder circuit breaker when there is a flight control problem. In spite of pointing this out to him, he elected not to comply, as he could not find the reference. Recommendation: note in the 'leading edge flap asymmetry' procedure pointing out that the 'leading edge slat disagree' light will normally come on, and has no effect on procedure or confign requirements. More narrative regarding leading edge mechanicals and if there is much of a threat in cruise of them extending uncommanded.

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Original NASA ASRS Text

Title: 'LEADING SLAT ASYMMETRY AND LEADING EDGE' CAUTION LIGHT CAME ON IN CRUISE. NO APPARENT CTL PROB SO CONSIDERED A FAULTY INDICATION. PRECAUTIONS FOLLOWED FOR LNDG.

Narrative: AT CRUISE FL350 WITH NO SPD OR CONFIGN CHANGES, OBSERVED 'LEADING EDGE ASYMMETRY' EICAS MESSAGE AND 'LEADING EDGE' CAUTION LIGHT. NO SECONDARY INDICATIONS WERE OBSERVED. THIS INCLUDED A VISUAL INSPECTION, AND TAKING THE PHYSICAL CTL OF THE ACFT WITH THE AUTOPLT OFF. THE EMER PROC IS WRITTEN FOR A CONFIGN CHANGE SIT. THERE IS A CAUTION TO MAINTAIN 240 KIAS OR LESS IN THE PROC DUE TO LEADING EDGE LIMITATIONS. I LEANED TOWARDS MAINTAINING THIS SPD OR LESS, AS WE DIDN'T KNOW THE FULL EXTENT OF THE PROB AND THE OPERATING MANUAL IS NOT VERY DESCRIPTIVE OF MECHANICAL PROTECTION DEVICES, DESIGN, ETC. THE CAPT FELT THAT IT WAS AN INDICATION PROB, AND BELIEVED THAT THERE WAS LITTLE DANGER OF AGGRAVATING THE SIT. UPON ARR AT ORD WE ADVISED APCH OF HIGHER APCH SPDS, AND THE NEED FOR AN EXTENDED FINAL. WHEN CONFIGURING FOR LNDG AND ELECTRICALLY EXTENDING TRAILING EDGE FLAPS, RECEIVED A 'LEADING EDGE SLAT DISAGREE' LIGHT. THIS IS NORMAL FOR THE ASYMMETRY SIT, BUT IT IS NOT NOTED IN THE PROC. WHILE WE HAD REVIEWED THE OPERATING MANUAL, AND SYS KNOWLEDGE SHOULD'VE PRECLUDED ANY CONFUSION HERE, IT WAS DEFINITELY A DISTR TO REVIEW ANOTHER EXTENSIVE EMER PROC, TO ENSURE THAT NOTHING IN IT APPLIED. AT THE COMPLETION OF THE FLT, THE CAPT WAS UNAWARE OF THE REQUIREMENT TO PULL THE COCKPIT VOICE RECORDER CIRCUIT BREAKER WHEN THERE IS A FLT CTL PROB. IN SPITE OF POINTING THIS OUT TO HIM, HE ELECTED NOT TO COMPLY, AS HE COULD NOT FIND THE REF. RECOMMENDATION: NOTE IN THE 'LEADING EDGE FLAP ASYMMETRY' PROC POINTING OUT THAT THE 'LEADING EDGE SLAT DISAGREE' LIGHT WILL NORMALLY COME ON, AND HAS NO EFFECT ON PROC OR CONFIGN REQUIREMENTS. MORE NARRATIVE REGARDING LEADING EDGE MECHANICALS AND IF THERE IS MUCH OF A THREAT IN CRUISE OF THEM EXTENDING UNCOMMANDED.

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.