A piper PA31T cheyenne ii in cruise at FL200 declared an emergency and diverted due to a complete lo...

Attributes
ACN	373190
Time
Date	199706
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ykn
State Reference	SD
Altitude	msl bound lower : 20000 msl bound upper : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	general aviation : corporate
Make Model Name	PA-31T Cheyenne II
Operating Under FAR Part	Part 135
Flight Phase	cruise other other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : cfi pilot : commercial
Experience	flight time last 90 days : 45 flight time total : 10050 flight time type : 3000
ASRS Report	373190
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other flight crewa other other : unspecified cockpit
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

During normal cruise at FL200 I experienced a rapid decompression. I called center and advised him I was beginning an immediate descent due to loss of cabin pressure. He acknowledged but did not give me a clearance. Although a loss of cabin pressure at FL200 is not what some would call an emergency, I had onboard a passenger with asthma and was concerned for her well being. During the descent through about 15000 ft center called and inquired about my altitude. I verified that I was at 15000 ft, descending. He said that there was no problem and asked if I needed assistance. Still, I did descend without a clearance. Although there was no traffic conflict, if there had been traffic, if there had been a collision, that would not have been good for the well being of my passenger. In retrospect it may have been better to, use our oxygen masks, and delay the descent a min or two, in order to obtain a descent clearance. The masks were on already, anyway and it would not have been a problem to descend a couple of mins later. Callback conversation with reporter revealed the following information: reporter stated the aircraft was a piper cheyenne ii and the loss of pressurization was caused by a flexible heater duct clamp which was loose or broken allowing the duct to slip off the metal ducting.

Original NASA ASRS Text

Title: A PIPER PA31T CHEYENNE II IN CRUISE AT FL200 DECLARED AN EMER AND DIVERTED DUE TO A COMPLETE LOSS OF PRESSURIZATION CAUSED BY A FAILED FLEXIBLE HEATER DUCTING CLAMP.

Narrative: DURING NORMAL CRUISE AT FL200 I EXPERIENCED A RAPID DECOMPRESSION. I CALLED CTR AND ADVISED HIM I WAS BEGINNING AN IMMEDIATE DSCNT DUE TO LOSS OF CABIN PRESSURE. HE ACKNOWLEDGED BUT DID NOT GIVE ME A CLRNC. ALTHOUGH A LOSS OF CABIN PRESSURE AT FL200 IS NOT WHAT SOME WOULD CALL AN EMER, I HAD ONBOARD A PAX WITH ASTHMA AND WAS CONCERNED FOR HER WELL BEING. DURING THE DSCNT THROUGH ABOUT 15000 FT CTR CALLED AND INQUIRED ABOUT MY ALT. I VERIFIED THAT I WAS AT 15000 FT, DSNDING. HE SAID THAT THERE WAS NO PROB AND ASKED IF I NEEDED ASSISTANCE. STILL, I DID DSND WITHOUT A CLRNC. ALTHOUGH THERE WAS NO TFC CONFLICT, IF THERE HAD BEEN TFC, IF THERE HAD BEEN A COLLISION, THAT WOULD NOT HAVE BEEN GOOD FOR THE WELL BEING OF MY PAX. IN RETROSPECT IT MAY HAVE BEEN BETTER TO, USE OUR OXYGEN MASKS, AND DELAY THE DSCNT A MIN OR TWO, IN ORDER TO OBTAIN A DSCNT CLRNC. THE MASKS WERE ON ALREADY, ANYWAY AND IT WOULD NOT HAVE BEEN A PROB TO DSND A COUPLE OF MINS LATER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE ACFT WAS A PIPER CHEYENNE II AND THE LOSS OF PRESSURIZATION WAS CAUSED BY A FLEXIBLE HEATER DUCT CLAMP WHICH WAS LOOSE OR BROKEN ALLOWING THE DUCT TO SLIP OFF THE METAL DUCTING.

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.

A piper PA31T cheyenne ii in cruise at FL200 declared an emergency and diverted due to a complete loss of pressurization caused by a failed flexible heater ducting clamp.