Narrative:

This report involves a B727 modified with the dugan quiet wing system and its subsequent degraded landing performance. I had read in industry pubs of how this modification would enable the B727 to meet the stage 3 noise requirements and was vaguely familiar with its workings. This and word of mouth from our company operations personnel equated it to a robertson STOL 337 stc (installed on GA aircraft for yrs) with the center engine reverser removed. When the first aircraft was ready, a differences section was appended to the aom but no additional training was given to flcs. From reading the flight manuals every indication was that the airplane was to be normally landed at flaps 30 degrees with 40 degrees being for emergency use only. This did not particularly cause any concern or even hint of uniqueness with me as I had experience some 40 yrs prior with a B737 that was flaps 30 degrees and 40 degrees limited for emergency use only as part of a program meeting the earlier noise requirements. During this time I had learned that landing at flaps 25 degrees (after many yrs of only flaps 40 degrees) did make a large difference in the landing roll both north float and increased stopping distance after touchdown. Once a pilot knew of these characteristics appropriate caution could be taken. Prior to and for several weeks after this landing event, I fully believed that I was actually landing at flaps 30 degrees and I had never been told anything to the contrary and no sequence of events ever arose to concern me. Our destination airport and its noise abatement program routinely has traffic using a landing runway that may not be directly oriented into the wind and this day was no exception. The assigned runway gave us a slight quartering tailwind of only several KTS, well below the limitations of this aircraft. Touchdown was accomplished with an often used method of applying some power in order to arrest sink rate. This again did not concern me as I had seen it done hundreds of times with no noticeable landing distance increase. This was the first flight for the highly experienced first officer in the quiet wing system and he remakred of its lack of stopping ability after more than normal braking was required. I attributed it to the lack of the center engine reverser for, as mentioned earlier, I still did not know that we were actually landing at or very close to 25 degrees flaps! It was not until some time later during a proficiency check that a fellow pilot whom had taken the time to dig very deeply into the specifics of the quiet wing system enlightened me to the true facts and operation of this modified wing. I was both shocked and appalled that I had been allowed, through insufficient training (it was not required by the FAA) to operate a jet transport aircraft at essentially a flaps 25 degree landing without even knowing it! If I had known, the appropriate level of caution would have been exercised as mentioned earlier. The above and continuing and extremely poor and confusing technical support by the manufacturer continues to plague we pilots as we operate this system. This means we are continually faced with problems such as an improper and confusing flap operating and indicating apparatus and very unrealistic performance figures. To boot, we are asked to operate it into a runway shorter than normal for jet transport aircraft that is oftentimes very slippery! Our pilot force was given additional training, but for a safety enhancement, any other operator should be made well aware that this is a reduced drag landing configured aircraft, no installation should be allowed without an improved flap indicator and the supplemental performance manual should be corrected for errors. Callback conversation with reporter revealed the following information: the reporter stated that the union safety and engineering knows of this problem and suggested that he report this incident. The FAA is also aware of this modification. There has been a near runway excursion since these aircraft were modified. The reporter is concerned that a crew might perform a landing with a slight tailwind without understanding the critical nature of the tendency of the aircraft to use more runway than expected. He would like the gauges to indicate the actual 25 degree settings and that the crews be restr to a no tailwind component. To his knowledge, the company landing weights are based upon the 30 degree setting, with their stance being taken that the 03 degree position is the same landing performance as the 25 degrees. His second concern was that the flaps quadrant does not have a stop detent from the landing flap detent of '30' (25) degrees position towards the up position until flap 2 degrees position. There should be a stop at the 15 degree position. Crews might retract flaps to that 2 degree position on a missed approach/go around too soon when only a 15 degree position is desired.

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Original NASA ASRS Text

Title: A B727-200 PIC RPT ON THE REDUCED DRAG AND INCREASED BRAKING REQUIREMENTS WHEN LNDG THEIR ACFT WITH FLAPS 30 DEGS WITH THE DUGAN QUIET WING SYS AT ZZZ, US.

Narrative: THIS RPT INVOLVES A B727 MODIFIED WITH THE DUGAN QUIET WING SYS AND ITS SUBSEQUENT DEGRADED LNDG PERFORMANCE. I HAD READ IN INDUSTRY PUBS OF HOW THIS MODIFICATION WOULD ENABLE THE B727 TO MEET THE STAGE 3 NOISE REQUIREMENTS AND WAS VAGUELY FAMILIAR WITH ITS WORKINGS. THIS AND WORD OF MOUTH FROM OUR COMPANY OPS PERSONNEL EQUATED IT TO A ROBERTSON STOL 337 STC (INSTALLED ON GA ACFT FOR YRS) WITH THE CTR ENG REVERSER REMOVED. WHEN THE FIRST ACFT WAS READY, A DIFFERENCES SECTION WAS APPENDED TO THE AOM BUT NO ADDITIONAL TRAINING WAS GIVEN TO FLCS. FROM READING THE FLT MANUALS EVERY INDICATION WAS THAT THE AIRPLANE WAS TO BE NORMALLY LANDED AT FLAPS 30 DEGS WITH 40 DEGS BEING FOR EMER USE ONLY. THIS DID NOT PARTICULARLY CAUSE ANY CONCERN OR EVEN HINT OF UNIQUENESS WITH ME AS I HAD EXPERIENCE SOME 40 YRS PRIOR WITH A B737 THAT WAS FLAPS 30 DEGS AND 40 DEGS LIMITED FOR EMER USE ONLY AS PART OF A PROGRAM MEETING THE EARLIER NOISE REQUIREMENTS. DURING THIS TIME I HAD LEARNED THAT LNDG AT FLAPS 25 DEGS (AFTER MANY YRS OF ONLY FLAPS 40 DEGS) DID MAKE A LARGE DIFFERENCE IN THE LNDG ROLL BOTH N FLOAT AND INCREASED STOPPING DISTANCE AFTER TOUCHDOWN. ONCE A PLT KNEW OF THESE CHARACTERISTICS APPROPRIATE CAUTION COULD BE TAKEN. PRIOR TO AND FOR SEVERAL WKS AFTER THIS LNDG EVENT, I FULLY BELIEVED THAT I WAS ACTUALLY LNDG AT FLAPS 30 DEGS AND I HAD NEVER BEEN TOLD ANYTHING TO THE CONTRARY AND NO SEQUENCE OF EVENTS EVER AROSE TO CONCERN ME. OUR DEST ARPT AND ITS NOISE ABATEMENT PROGRAM ROUTINELY HAS TFC USING A LNDG RWY THAT MAY NOT BE DIRECTLY ORIENTED INTO THE WIND AND THIS DAY WAS NO EXCEPTION. THE ASSIGNED RWY GAVE US A SLIGHT QUARTERING TAILWIND OF ONLY SEVERAL KTS, WELL BELOW THE LIMITATIONS OF THIS ACFT. TOUCHDOWN WAS ACCOMPLISHED WITH AN OFTEN USED METHOD OF APPLYING SOME PWR IN ORDER TO ARREST SINK RATE. THIS AGAIN DID NOT CONCERN ME AS I HAD SEEN IT DONE HUNDREDS OF TIMES WITH NO NOTICEABLE LNDG DISTANCE INCREASE. THIS WAS THE FIRST FLT FOR THE HIGHLY EXPERIENCED FO IN THE QUIET WING SYS AND HE REMAKRED OF ITS LACK OF STOPPING ABILITY AFTER MORE THAN NORMAL BRAKING WAS REQUIRED. I ATTRIBUTED IT TO THE LACK OF THE CTR ENG REVERSER FOR, AS MENTIONED EARLIER, I STILL DID NOT KNOW THAT WE WERE ACTUALLY LNDG AT OR VERY CLOSE TO 25 DEGS FLAPS! IT WAS NOT UNTIL SOME TIME LATER DURING A PROFICIENCY CHK THAT A FELLOW PLT WHOM HAD TAKEN THE TIME TO DIG VERY DEEPLY INTO THE SPECIFICS OF THE QUIET WING SYS ENLIGHTENED ME TO THE TRUE FACTS AND OP OF THIS MODIFIED WING. I WAS BOTH SHOCKED AND APPALLED THAT I HAD BEEN ALLOWED, THROUGH INSUFFICIENT TRAINING (IT WAS NOT REQUIRED BY THE FAA) TO OPERATE A JET TRANSPORT ACFT AT ESSENTIALLY A FLAPS 25 DEG LNDG WITHOUT EVEN KNOWING IT! IF I HAD KNOWN, THE APPROPRIATE LEVEL OF CAUTION WOULD HAVE BEEN EXERCISED AS MENTIONED EARLIER. THE ABOVE AND CONTINUING AND EXTREMELY POOR AND CONFUSING TECHNICAL SUPPORT BY THE MANUFACTURER CONTINUES TO PLAGUE WE PLTS AS WE OPERATE THIS SYS. THIS MEANS WE ARE CONTINUALLY FACED WITH PROBS SUCH AS AN IMPROPER AND CONFUSING FLAP OPERATING AND INDICATING APPARATUS AND VERY UNREALISTIC PERFORMANCE FIGURES. TO BOOT, WE ARE ASKED TO OPERATE IT INTO A RWY SHORTER THAN NORMAL FOR JET TRANSPORT ACFT THAT IS OFTENTIMES VERY SLIPPERY! OUR PLT FORCE WAS GIVEN ADDITIONAL TRAINING, BUT FOR A SAFETY ENHANCEMENT, ANY OTHER OPERATOR SHOULD BE MADE WELL AWARE THAT THIS IS A REDUCED DRAG LNDG CONFIGURED ACFT, NO INSTALLATION SHOULD BE ALLOWED WITHOUT AN IMPROVED FLAP INDICATOR AND THE SUPPLEMENTAL PERFORMANCE MANUAL SHOULD BE CORRECTED FOR ERRORS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT THE UNION SAFETY AND ENGINEERING KNOWS OF THIS PROB AND SUGGESTED THAT HE RPT THIS INCIDENT. THE FAA IS ALSO AWARE OF THIS MODIFICATION. THERE HAS BEEN A NEAR RWY EXCURSION SINCE THESE ACFT WERE MODIFIED. THE RPTR IS CONCERNED THAT A CREW MIGHT PERFORM A LNDG WITH A SLIGHT TAILWIND WITHOUT UNDERSTANDING THE CRITICAL NATURE OF THE TENDENCY OF THE ACFT TO USE MORE RWY THAN EXPECTED. HE WOULD LIKE THE GAUGES TO INDICATE THE ACTUAL 25 DEG SETTINGS AND THAT THE CREWS BE RESTR TO A NO TAILWIND COMPONENT. TO HIS KNOWLEDGE, THE COMPANY LNDG WTS ARE BASED UPON THE 30 DEG SETTING, WITH THEIR STANCE BEING TAKEN THAT THE 03 DEG POS IS THE SAME LNDG PERFORMANCE AS THE 25 DEGS. HIS SECOND CONCERN WAS THAT THE FLAPS QUADRANT DOES NOT HAVE A STOP DETENT FROM THE LNDG FLAP DETENT OF '30' (25) DEGS POS TOWARDS THE UP POS UNTIL FLAP 2 DEGS POS. THERE SHOULD BE A STOP AT THE 15 DEG POS. CREWS MIGHT RETRACT FLAPS TO THAT 2 DEG POS ON A MISSED APCH/GAR TOO SOON WHEN ONLY A 15 DEG POS IS DESIRED.

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.