AC69 pilot experiences static system failure at FL250 after departing following a heavy rainstorm.

Attributes
ACN	742877
Time
Date	200705
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sat.airport
State Reference	TX
Altitude	msl single value : 25000
Environment
Flight Conditions	VMC
Weather Elements	Ice Thunderstorm
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu.artcc tower : lax.tower
Operator	general aviation : corporate
Make Model Name	Rockwell Aero Commander Twin Turboprop Undifferentiated or Other
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Route In Use	departure sid : alamo
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 60 flight time total : 10900 flight time type : 5000
ASRS Report	742877
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather
Independent Detector	other flight crewa
Resolutory Action	aircraft : equipment problem dissipated controller : provided flight assist controller : issued new clearance flight crew : exited adverse environment
Supplementary
Problem Areas	Aircraft Weather
Primary Problem	Aircraft

Narrative:

We had to wait 30 mins for an area of heavy rain to pass through. We depart sat about XA00 lct; on the alamo 6; lufken transition; my final altitude was FL250. We had to leveloff at FL240 for about 10 mins for traffic. (There was 1 hole through the thunderstorm.) when cleared to climb from FL240 to FL250; I engaged the altitude pre-select. After changing frequency while climb; I noticed the airspeed was decreasing as we climbed. When the aircraft leveled at FL250 the airspeed was zero. We never encountered any ice and the pitot heat was on. So I select the alternate static source. The altimeter began to climb. I finally shut it off and stop the climb at FL220. Even though I was at FL250 the GPS verified me at FL250. I notified center of my problem and asked for an altitude below FL180 so I could go VFR. Note -- the OAT was -10 degrees C. When reaching 15000 ft; everything indicated correctly. I could only figure water from the hard rain at sat; must have entered the system and froze while at FL240. We had the system checked the next day and found nothing wrong.

Original NASA ASRS Text

Title: AC69 PLT EXPERIENCES STATIC SYSTEM FAILURE AT FL250 AFTER DEPARTING FOLLOWING A HEAVY RAINSTORM.

Narrative: WE HAD TO WAIT 30 MINS FOR AN AREA OF HVY RAIN TO PASS THROUGH. WE DEPART SAT ABOUT XA00 LCT; ON THE ALAMO 6; LUFKEN TRANSITION; MY FINAL ALT WAS FL250. WE HAD TO LEVELOFF AT FL240 FOR ABOUT 10 MINS FOR TFC. (THERE WAS 1 HOLE THROUGH THE TSTM.) WHEN CLRED TO CLB FROM FL240 TO FL250; I ENGAGED THE ALT PRE-SELECT. AFTER CHANGING FREQ WHILE CLB; I NOTICED THE AIRSPD WAS DECREASING AS WE CLBED. WHEN THE ACFT LEVELED AT FL250 THE AIRSPD WAS ZERO. WE NEVER ENCOUNTERED ANY ICE AND THE PITOT HEAT WAS ON. SO I SELECT THE ALTERNATE STATIC SOURCE. THE ALTIMETER BEGAN TO CLB. I FINALLY SHUT IT OFF AND STOP THE CLB AT FL220. EVEN THOUGH I WAS AT FL250 THE GPS VERIFIED ME AT FL250. I NOTIFIED CTR OF MY PROB AND ASKED FOR AN ALT BELOW FL180 SO I COULD GO VFR. NOTE -- THE OAT WAS -10 DEGS C. WHEN REACHING 15000 FT; EVERYTHING INDICATED CORRECTLY. I COULD ONLY FIGURE WATER FROM THE HARD RAIN AT SAT; MUST HAVE ENTERED THE SYS AND FROZE WHILE AT FL240. WE HAD THE SYS CHKED THE NEXT DAY AND FOUND NOTHING WRONG.

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.