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January 26, 1985 · Boeing 727-51 · N463US
St. Paul, MN
Overview
Report Status
Preliminary report
Event Type
Incident
Date
January 26, 1985
Injury Outcomes
No injuries (61 uninjured)
Location
St. Paul, MN
Aircraft
Boeing 727-51
Tail Number
N463US
Injuries
None
Aircraft Damage
Minor
NTSB Number
CHI85IA097
SHORTLY AFTER TAKEOF, THE AIRCRAFT EXPERIENCED AN UNCONTAINED 7TH TO 8TH STAGE REMOVABLE SLEEVE COMPRESSOR SPACER FAILURE IN THE NUMBER 3 ENGINE. PIECES OF THE SPACER PASSED THROUGH THE NUMBER 2 ENGINES DUCT CAUSING COMPRESSOR STALLS IN THAT ENGINE. THE AIRCRAFT LANDED SUCESSFULLY 9 MINUTES AFTER TAKEOFF USING THE SINGLE GOOD ENGINE. METALLURGICAL ANALYSIS OF THE RECOVERED SPACER PIECES REVEALED THAT CADMIUM EMBRITTLEMENT HAD OCCURRED AROUND AT LEAST ONE TIEROD SLEEVE HOLE ON THE SPACER. THIS EMBRITTLEMENT OCCURRED BECAUSE THE SPACER WAS INCOMPLETELY PLATED WITH NICKLE DURING A SPACER MODIFICATION THAT TOOK PLACE IN 1975. THE INCOMPLETE NICKLE PLATING ALLOWED A SUBSEQUENT CADIUM LAYER TO COME IN CONTACT WITH THE STEEL SPACER, CAUSING THE EMBRITTLEMENT.
Full Narrative
SHORTLY AFTER TAKEOF, THE AIRCRAFT EXPERIENCED AN UNCONTAINED 7TH TO 8TH STAGE REMOVABLE SLEEVE COMPRESSOR SPACER FAILURE IN THE NUMBER 3 ENGINE. PIECES OF THE SPACER PASSED THROUGH THE NUMBER 2 ENGINES DUCT CAUSING COMPRESSOR STALLS IN THAT ENGINE. THE AIRCRAFT LANDED SUCESSFULLY 9 MINUTES AFTER TAKEOFF USING THE SINGLE GOOD ENGINE. METALLURGICAL ANALYSIS OF THE RECOVERED SPACER PIECES REVEALED THAT CADMIUM EMBRITTLEMENT HAD OCCURRED AROUND AT LEAST ONE TIEROD SLEEVE HOLE ON THE SPACER. THIS EMBRITTLEMENT OCCURRED BECAUSE THE SPACER WAS INCOMPLETELY PLATED WITH NICKLE DURING A SPACER MODIFICATION THAT TOOK PLACE IN 1975. THE INCOMPLETE NICKLE PLATING ALLOWED A SUBSEQUENT CADIUM LAYER TO COME IN CONTACT WITH THE STEEL SPACER, CAUSING THE EMBRITTLEMENT.
Flight
Event TypeIncident
Event Time14:29 CST
Nearest AirportMinneapolis/St. Paul Arpt (0nm N)
Runway0
Runway Length0
Runway Width0
Flight Plan FiledIFR
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftBoeing 727-51
Tail NumberN463US
Aircraft CategoryAir
DamageMinor
Operating RulePart 121
Engines3
Engine TypeTurbojet
Engine DetailsP&W · JT8D-7B · Turbojet · 12600
Seats134
People & Injuries
Injury SummaryNo injuries (61 uninjured)
Fatal0
Serious0
Minor0
Uninjured61
Total61
Crew 1Age 47 · First Class
Conditions
ConditionsIMC
LightDaylight
Wind240° @ 11 kt
Visibility7 sm
CeilingNone
Temperature / Dew Point18 C / 5 C
Altimeter29.00 inHg
Observation Time19:50
Weather SourceWFAC