PA-46 pilot reports fluctuating manifold pressure at FL210 and the inability to contact ATC. A desce...

Attributes
ACN	1100571
Time
Date	201306
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	PA-46 Malibu Meridian
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Reciprocating Engine Assembly
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Commercial Flight Crew Instrument
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 1500 Flight Crew Type 700
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy

Narrative:

Experienced manifold pressure fluctuation at FL210 in cruise flight. After several minutes; manifold pressure was steadily decreasing. [I] called center to report a problem with no answer on last assigned frequency. After several more attempts; as well as an attempt to contact them on 121.5 MHZ; all with no response; the manifold pressure was approaching a level where cabin pressurization could not be maintained. Pilot in command executed a descent from FL210 for lower altitude; while attempting to troubleshoot the problem and find the correct frequency for center due to a missed handoff. After locating the correct center frequency; and making contact with the controller; I advised them of my altitude and reason for immediate descent from FL210. I asked the controller for an immediate descent to a lower altitude; while I troubleshot the manifold pressure problem. They issued me a new clearance to FL160. I also advised them that I was not handed off to the next controller correctly; and the altitude deviation from FL210 was necessary to avoid a possible cabin pressurization emergency. Manifold pressure was restored at the lower altitude and the flight was continued to the destination.note: I was monitoring 121.5 MHZ during the entire flight; and did not hear any attempt from center to contact me.

Original NASA ASRS Text

Title: PA-46 pilot reports fluctuating manifold pressure at FL210 and the inability to contact ATC. A descent is initiated before communications can be established due to the possibility of losing cabin pressurization. At 16;000 feet MAP is normal and flight continues to destination.

Narrative: Experienced manifold pressure fluctuation at FL210 in cruise flight. After several minutes; manifold pressure was steadily decreasing. [I] called Center to report a problem with no answer on last assigned frequency. After several more attempts; as well as an attempt to contact them on 121.5 MHZ; all with no response; the manifold pressure was approaching a level where cabin pressurization could not be maintained. Pilot in Command executed a descent from FL210 for lower altitude; while attempting to troubleshoot the problem and find the correct frequency for Center due to a missed handoff. After locating the correct Center frequency; and making contact with the Controller; I advised them of my altitude and reason for immediate descent from FL210. I asked the Controller for an immediate descent to a lower altitude; while I troubleshot the manifold pressure problem. They issued me a new clearance to FL160. I also advised them that I was not handed off to the next Controller correctly; and the altitude deviation from FL210 was necessary to avoid a possible cabin pressurization emergency. Manifold pressure was restored at the lower altitude and the flight was continued to the destination.Note: I was monitoring 121.5 MHZ during the entire flight; and did not hear any attempt from Center to contact me.

Data retrieved from NASA's ASRS site as of July 2013 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.

PA-46 pilot reports fluctuating manifold pressure at FL210 and the inability to contact ATC. A descent is initiated before communications can be established due to the possibility of losing cabin pressurization. At 16;000 feet map is normal and flight continues to destination.