Bombardier CL-65 N97325

Summary

On 19 July 2000 at about 01:45 local time, a Bombardier CL-65 registered N97325 was involved in an incident near Monterey, California, United States. 23 people were on board and nobody was injured. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

19 July 2000 at 01:45

Classification

Incident

Location

Monterey, California, United States

Coordinates

36.6006, -121.8806

Aircraft

Bombardier CL-65

Registration

N97325

Category

Airplane

Engines

2

Operator

Not recorded

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Monterey → Phoenix

Aircraft damage

Not recorded

Weather

VMC

Light

Day

NTSB number

LAX00IA272

Nobody was injured.

Fatigue failure of the bell gear in the horizontal stabilizer trim actuator system.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

While climbing through FL200, the autopilot pitch trim master caution warning light and the autopilot pitch trim nose down master caution warning light illuminated, and the trim froze at four units of trim. The autopilot was disengaged in accordance with AFM procedures to resolve the problem. The flight crew had to maintain about 2 inches of forward pressure on the flight control column to maintain level flight. The first officer reported that the stabilizer trim could be manually adjusted up and down, but at no point would the trim go below four units of trim. The Horizontal Stabilizer Trim Actuator (HSTA) and Motor Control Unit (MCU) were replaced, and the airplane underwent a series of diagnostic checks and a functional flight test with no mechanical anomalies noted. During removal of the HSTA and MCU a component was heard moving inside the HSTA. Teardown of the HSTA revealed that the Channel 1 bell gear had separated from its four mounting tabs. It was also noted that two of the main spur gear bolts had backed out, and were loose and out of position in the HSTA. The other two main spur gear bolts were finger-tight, but remained in place. SB 8396-27-02 was developed as a result of repeated bell gear failures, about 66 in the past 6 years. The SB called for replacement of the existing bell gear with a new stronger bell gear. SL 8396-27-01 resulted from repeated main spur gear bolts backing out in service. The main spur gear bolts now require Loctite be used with the new bolts and new torque values be applied to the bolts. Review of the operator's FAA approved Operating Specifications disclosed that compliance with manufacturers SB's and SL's is not mandatory.

Quoted verbatim from the NTSB record.