N451GA

ATA 3411

OPERATOR NOTIFIED THAT THE ABOVE ACFT HAD BEEN RECORDED 200' LOW ON A RVSM HEIGHT MONITORING STA. A COMPLETE 91.411 AND 91.413 CHECK WAS COMPLETED WITH NO FAULT FOUND. ALL SYS SHOWED NO SIGNIFICANT ERRORS OR LEAKAGE. IT WAS LATER DISCOVERED THAT DURING THE PITOT STATIC CHECKS THAT THE TECH ONLY PLUMBED THE TEST EQUIPMENT INTO THE LT SIDE STATIC PORTS. THIS ACFT HAS 2 STATIC PORTS FOR EACH AIR-DATA COMPUTER, PILOTS LT & RT AS WELL AS COPILOTS LT & RT. WHEN EACH PORT WAS CHECKED INDIVIDUALLY THE PILOT’S RT STATIC PORT WAS FOUND TO BE BLOCKED BY WHAT APPEARED TO BE MUD OR BUG DEBRIS. THIS CONDITION WOULD CAUSE A STATIC PRESSURE IMBALANCE CAUSING AN ALTITUDE ERROR. THE STATIC PORT WAS PURGED AND CLEARED AND THE ACFT RETURNED TO SERVICE. THIS IS THE SECOND TIME THE SUBMITTER HAS SEEN THIS CONDITION AND SUGGESTS THAT DURING THE 24 MONTH PITOT STATIC RECERTIFICATION THAT ALL PORTS AND PROBES BE CHECKED INDIVIDUALLY FOR OPERATION AND BLOCKAGES.

ATA 2120

THE CREW REPORTED THAT THE AIRCRAFT WAS DIFFICULT TO COOL AFTER BEING HEAT SOAKED. TECHNICIANS UPON TROUBLESHOOTING FOUND VERY LOW AIRFLOW FROM THE LEFT AND RIGHT FLOOR DISTRIBUTION DUCTS. USING A BOROSCOPE AND HAND MIRRORS IT WAS DETERMINED THAT THE AIR HOLES IN THE DISTRIBUTION DUCTS WERE CLOGGED WITH A FOAM MATERIAL. THE DUCTS WERE REMOVED AND LARGE AMOUNTS OF FOAM MATERIAL HAD TO BE REMOVED. THE SOURCE WAS DETERMINED TO BE THE CABIN AIR SILENCER GAC P/N 1159AC20113-1. INTERNAL BAFFLING FOAM HAD DETERIORATED AND THE FOAM TRAVELED ALONG THE AIR DISTRIBUTION DUCTS IN THE CABIN CLOGGING THE OUTPUT HOLES. THIS IS A KNOWN ISSUE WITH THIS SILENCER. CLEANING THE DUCTS AND REPLACING THE CABIN SILENCER RETURNED THE SYSTEM TO NORMAL.