BE58 HAS LOSS OF MANIFOLD PRESSURE AT FL220.

Narrative

SHORTLY AFTER REACHING FL220; I OBSERVED THE MANIFOLD PRESSURE AT 20 INCHES BELOW THE 30 INCHES NORMAL CRUISE. MOST LIKELY THE WASTE GATE CLOSED AND WOULD NOT ALLOW THE ACFT TO GENERATE THE NORMAL 30 INCHES. OPENING THE COWL FLAPS AND ENRICHENING THE MIXTURE DID NOT RESOLVE THE PROB. I ADVISED CTR I NEEDED TO GO BACK TO CLT. NO EMER WAS DECLARED AND PRIORITY WAS REQUESTED. AS A DSCNT WAS MADE THE MANIFOLD PRESSURE BEGAN TO CLB AS IN A NORMAL ASPIRATED ENG. A NORMAL APCH AND LNDG WITHOUT FURTHER INCIDENT WAS MADE. NO FURTHER RPT TO ATC WAS SUBMITTED. RECOMMEND PLTS INVOLVED IN SUCH SITS TO MONITOR CYLINDER HEAD TEMP; OIL PRESSURE AND TEMP INDICATIONS TO AVOID EXCEEDING LIMITS WHEN SUCH CONDITIONS OCCUR. ANY INDICATION OF FAILING ENG SHOULD NECESSITATE SHUTTING DOWN THE ENG TO PREVENT DAMAGE TO INTERNAL COMPONENTS; AND PROPER FEATHERING OF THE PROP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THE PROB WAS A CRACKED CYLINDER. THE TURBO COULD NOT COMPRESS DUE TO THE CRACK AND THE MANIFOLD PRESSURE COULD NOT BE SUSTAINED. HE MENTIONED THE CYLINDER HEAD TEMP BECAUSE THE NEEDLE WAS FLUCTUATING A GREAT DEAL AND WAS OF CONCERN TO FLC. THEY FOUND OUT THAT THE CRACK WAS AT THE POINT WHERE THE CYLINDER HEAD TEMP PROBE WAS LOCATED AND THE PROBE WAS ALTERNATELY GETTING COLD AIR AND WARM AIR CAUSING THIS FLUCTUATION. CYLINDER HAS BEEN REPAIRED AND THE ACFT WORKS LIKE A CHARM.