|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||airport : zzz.airport|
|Altitude||msl single value : 5000|
|Controlling Facilities||artcc : zzz.artcc|
|Operator||general aviation : personal|
|Make Model Name||SR20|
|Operating Under FAR Part||Part 91|
|Flight Phase||climbout : initial|
climbout : intermediate altitude
|Function||flight crew : single pilot|
|Qualification||pilot : commercial|
pilot : cfi
|Experience||flight time last 90 days : 75|
flight time total : 5000
flight time type : 50
|Function||flight crew : single pilot|
|Anomaly||inflight encounter : weather|
inflight encounter other
|Independent Detector||other flight crewa|
|Resolutory Action||flight crew : diverted to another airport|
flight crew : exited adverse environment
|Consequence||faa : reviewed incident with flight crew|
Flight Crew Human Performance
|Primary Problem||Flight Crew Human Performance|
I departed on an IFR cross country flight in VFR conditions and was cleared to climb to 9000 ft. Bases were around 4000 ft MSL; roughly 3000 ft AGL; and cloud tops were 6000 ft. It was clear above. As soon as I entered the clouds; I picked up a trace of ice on the wings. Even though; by myself in the plane; I was climbing at 800 ft per minute; the climb rate dropped dramatically with a very small amount of icing. It was mixed rime ice. I tried to climb longer than I should; and to my surprise; the plane buffeted in a stall at about 100 KTS indicated airspeed. With a small amount of ice; the plane's ability to climb or fly at slower speeds was gone. I immediately initiated a turn and descent to escape the ice into VFR conditions below. I advised ATC accordingly; but did not declare an emergency. Even at cruise speed; the sr-20 handled as if it were at minimum control airspeed. A total of about 1/4 inch of rime ice formed. While not yet out of the clouds and at more than 1000 ft per minute descent; the control stick felt stuck. The elevator would not move. It took an unknown amount of force to break it loose as ice had formed on the tail. I elected to 'fly the plane to the runway' at cruise speed rather than risk the effect of a dramatically increased stall speed. Luckily the runway was very long. The design of the elevator balance weight and horizontal stabilizer is such that even a small amount of icing has potential to lock control of the elevator. Having encountered this problem; this design is alarming. The elevator balance weight should be sheltered behind the stabilizer leading edge; and there should be an adequate gap to disallow potential ice interference with control. Furthermore; cirrus pilots should be warned that the effect of even a small amount of icing is devastating to the performance of the laminar flow wing. I believe the kind and shape of icing results in huge variations in performance with this kind of wing.callback conversation with reporter revealed the following information: the reporter indicated that he did not think about using the cirrus parachute because he was too busy attending to flying the aircraft. The reporter stated that he was very concerned about sloughing ice asymmetrically; allowing one wing to stall and subsequently losing control of the aircraft.
Original NASA ASRS Text
Title: AN SR20 PLT ENCOUNTERED ICE; RESULTING IN A SERIOUS DEGRADATION IN PERFORMANCE AND LOSS OF ELEVATOR CTL.
Narrative: I DEPARTED ON AN IFR CROSS COUNTRY FLT IN VFR CONDITIONS AND WAS CLRED TO CLB TO 9000 FT. BASES WERE AROUND 4000 FT MSL; ROUGHLY 3000 FT AGL; AND CLOUD TOPS WERE 6000 FT. IT WAS CLEAR ABOVE. AS SOON AS I ENTERED THE CLOUDS; I PICKED UP A TRACE OF ICE ON THE WINGS. EVEN THOUGH; BY MYSELF IN THE PLANE; I WAS CLBING AT 800 FT PER MINUTE; THE CLB RATE DROPPED DRAMATICALLY WITH A VERY SMALL AMOUNT OF ICING. IT WAS MIXED RIME ICE. I TRIED TO CLB LONGER THAN I SHOULD; AND TO MY SURPRISE; THE PLANE BUFFETED IN A STALL AT ABOUT 100 KTS INDICATED AIRSPD. WITH A SMALL AMOUNT OF ICE; THE PLANE'S ABILITY TO CLB OR FLY AT SLOWER SPDS WAS GONE. I IMMEDIATELY INITIATED A TURN AND DSCNT TO ESCAPE THE ICE INTO VFR CONDITIONS BELOW. I ADVISED ATC ACCORDINGLY; BUT DID NOT DECLARE AN EMER. EVEN AT CRUISE SPD; THE SR-20 HANDLED AS IF IT WERE AT MINIMUM CTL AIRSPD. A TOTAL OF ABOUT 1/4 INCH OF RIME ICE FORMED. WHILE NOT YET OUT OF THE CLOUDS AND AT MORE THAN 1000 FT PER MINUTE DSCNT; THE CTL STICK FELT STUCK. THE ELEVATOR WOULD NOT MOVE. IT TOOK AN UNKNOWN AMOUNT OF FORCE TO BREAK IT LOOSE AS ICE HAD FORMED ON THE TAIL. I ELECTED TO 'FLY THE PLANE TO THE RWY' AT CRUISE SPD RATHER THAN RISK THE EFFECT OF A DRAMATICALLY INCREASED STALL SPD. LUCKILY THE RWY WAS VERY LONG. THE DESIGN OF THE ELEVATOR BALANCE WT AND HORIZONTAL STAB IS SUCH THAT EVEN A SMALL AMOUNT OF ICING HAS POTENTIAL TO LOCK CTL OF THE ELEVATOR. HAVING ENCOUNTERED THIS PROBLEM; THIS DESIGN IS ALARMING. THE ELEVATOR BALANCE WT SHOULD BE SHELTERED BEHIND THE STAB LEADING EDGE; AND THERE SHOULD BE AN ADEQUATE GAP TO DISALLOW POTENTIAL ICE INTERFERENCE WITH CTL. FURTHERMORE; CIRRUS PLTS SHOULD BE WARNED THAT THE EFFECT OF EVEN A SMALL AMOUNT OF ICING IS DEVASTATING TO THE PERFORMANCE OF THE LAMINAR FLOW WING. I BELIEVE THE KIND AND SHAPE OF ICING RESULTS IN HUGE VARIATIONS IN PERFORMANCE WITH THIS KIND OF WING.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR INDICATED THAT HE DID NOT THINK ABOUT USING THE CIRRUS PARACHUTE BECAUSE HE WAS TOO BUSY ATTENDING TO FLYING THE ACFT. THE RPTR STATED THAT HE WAS VERY CONCERNED ABOUT SLOUGHING ICE ASYMMETRICALLY; ALLOWING ONE WING TO STALL AND SUBSEQUENTLY LOSING CTL OF THE ACFT.
Data retrieved from NASA's ASRS site as of January 2009 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.