SDR 95ZZZX4608

Service difficulty report · Altitude Switch · Cessna 550

Difficulty date: August 25, 1995
Submitted: March 26, 2000
Operation: General aviation
Aircraft: N109GA
Make and model: Cessna 550
Aircraft serial: 5500124
System (JASC): 3520 · Passenger Oxygen System
Part: Altitude Switch
Part number: 99120575
Condition: Defective
Location: Oxygen System
Part time: 4,685 hours
Stage of operation: IN
Nature of condition: L
Precautionary procedure: K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

DURING PHASE 5 INSPECTION, OXYGEN SYSTEM FAILED FUNCTIONAL CHECK. OXYGEN MASK DEPLOYED AT 12,400 FEET WHEN THEY SHOULD DEPLOY AT 13,500 FEET, PLUS OR MINUS 600 FEET. DEFECTIVE BAROMETRIC ALTITUDE SWITCH CAUSED DISCREPANCY. INTERNAL FAILURE OF WEAKNESS OF SWITCH LIKELY CAUSE.

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