# NTSB SEA88IA028: Canadair CL600-2A12, N125PS, Twentynine Plms, CA, December 6, 1987

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: December 6, 1987, 13:23 local (21:23 UTC)
- Place: Twentynine Plms, CA
- Coordinates: 34.239566, -115.860145 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=34.2396&lon=-115.8601&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report July 10, 1989
- Report: Approved by Office Director
- NTSB case key (mKey): 40739
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA88IA028
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/40739/pdf
- Page: https://openairdocs.org/ntsb/SEA88IA028

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, climb - to cruise
  - water and waste system - leak (cause)
  - maintenance,installation - improper, unknown (cause)
  - autopilot/flight director,amplifier and computer - corroded (contributing factor)
  - flt control syst,rudder control - erratic (contributing factor)
- Loss of control - in flight, climb - to cruise
  - in-flight planning/decision - improper, copilot/second pilot (cause)
  - operation with known deficiencies in equipment - attempted, copilot/second pilot (cause)
  - autopilot/flight director - engaged (cause)

## Analysis

THE WATER FILTER HOUSING LOWER SEAL WAS MIS-INSTALLED WHICH ALLOWED WATER TO SEEP OUT AND RUN DOWN THE HOUSING CASE. OVER TIME THE WATER DROPPED ONTO A LAVATORY DRAIN LINE, FOLLOWED THE LINE TO A LOW POINT & COLLECTED ON THE STAB AUG COMPUTER BOX. THE FLUID ACCUMULATION RESULTED IN CORROSION ON ONE OF THE CIRCUIT BOARDS WITHIN THE COMPUTER BOX CAUSING A POWER IMBALANCE WITHIN THE YAW DAMPER SYSTEM AND A SUBSEQUENT UNCOMMANDED RUDDER SIGNAL. DRG THE CLIMB TO CRUISE TRANSITION A MACH TRIM FAILURE OCCURRED WHICH WOULD HAVE NECESSITATED THE USE OF THE AUTOPILOT FOR SPEEDS IN EXCESS OF 0.7 MACH. OPERATION OF THE AUTOPILOT, HOWEVER, RESULTED IN OPERATION OF THE YAW DAMPER SYSTEM WHICH HAD BEEN DETERMINED TO HAVE BEEN PRODUCING UNCOMMANDED RUDDER INPUTS. AS THE ACFT WAS LEVELLED AT FL330 AND THE AIRSPD WAS ALLOWED TO EXCEED MACH 0.7 THE COPLT ACTIVATED THE AUTOPLT WHICH POWERED THE MALFUNCTIONING DAMPER SYSTEM AND A DUTCH ROLL MANEUVER ENSUED. PIC DISCONNECTED THE AUTOPLT, EXECUTED A DESCENT AND RECOVERY.

## Aircraft

- Registration: [N125PS](https://openairdocs.org/deregistered/N125PS-2019-11-29), registration cancelled 2019-11-29, S/N 3058 (OpenAirDocs)
- Reported make and model: CANADAIR CL600-2A12
- Registry model: [Canadair CL-600-2A12](https://openairdocs.org/model/canadair-cl-600-2a12) (registry code 1900304) (OpenAirDocs)
- Registry engine: [GE CF-34-1A](https://openairdocs.org/engine/ge-cf-34-1a) (registry code 30033, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 3058
- Airframe hours: 336
- Engines: GE CF34-1A 8600 lbs thrust turbo fan
- Damage: No damage
- Flight: Personal, Part 91 subpart F
- Registered owner: Omni Restaurant Consulting Cor
- Airworthiness certificate: Standard, Transport
- Last inspection: 100 hour, October 29, 1987, 36 hours before
- Departed: SNA, SANTA ANA, CA
- Destination: LAS, LAS VEGAS, NV
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 49; airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: right; flight hours: 10,510 total, 325 in this make and model, 10,195 as pilot in command, 150 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 260° at 65 knots
- Visibility: 100 statute miles
- Lowest ceiling: none
- Temperature: 55 °F

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Incident 19871206075519I](https://openairdocs.org/incident/19871206075519I), Dec 6, 1987: Cndair CL6002A12, Twenty Nine Pal, CA. Dutch roll at FL330 due to yaw damper problem caused by leaky galley water filter. Turned off autopilot. Landed ok.

## Other investigations on N125PS (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB CEN12IA662](https://openairdocs.org/ntsb/CEN12IA662), Sep 21, 2012: Canadair CL-600 Challenger (N125PS), Denver, CO, incident, no damage. Probable cause: The internal failure of the galley heater mat’s thermostat, which resulted in an overheat condition.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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