AD 2011-12-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Bombardier | Various | Airworthiness Directives; Bombardier, Inc. Model CL-600-2C10 (Regional Jet Series 700, 701, & 702), Model CL-600-2D15 (Regional Jet Series 705), and Model CL-600-2D24 (Regional Jet Series 900) Airplanes |
| aircraft | Aviat | Various | Airworthiness Directives; Bombardier, Inc. Model CL-600-2C10 (Regional Jet Series 700, 701, & 702), Model CL-600-2D15 (Regional Jet Series 705), and Model CL-600-2D24 (Regional Jet Series 900) Airplanes |
Unsafe Condition
An inspection by the vendor revealed that a number of Rubber Bull Gears (RBG) in the Horizontal Stabilizer Trim Actuator (HSTA) of the CL-600-2C10, CL-600-2D15 and CL-600-2D24 aeroplanes were installed with a wheel material hardness out of specification. This non-conformity has a direct impact on the HSTA life limit. The teeth of these non-conformant RBGs could break and in extreme cases, could lead to uncontrolled HSTA movement without the ability to re-trim the aeroplane. If not corrected, this condition could result in a difficulty to control the pitch and subsequent loss of the aeroplane.
Required Actions
Replace the HSTA with a modified HSTA, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 670BA-27-058, dated August 31, 2010. The replacement must be done within the compliance times specified in the AD.
Compliance Time
Within 3,000 flight cycles from the effective date of this AD, or before the HSTA has accumulated 10,500 flight cycles, whichever occurs first, for HSTAs that have accumulated 8,700 total flight cycles or less as of the effective date of this AD. Within 1,800 flight cycles after the effective date of this AD, for HSTAs that have accumulated more than 8,700 total flight cycles as of the effective date of this AD.
Affected Aircraft
Bombardier, Inc. Model CL-600-2C10 (Regional Jet Series 700, 701, & 702), Model CL-600-2D15 (Regional Jet Series 705), and Model CL-600-2D24 (Regional Jet Series 900) airplanes, certificated in any category, equipped with a horizontal stabilizer trim actuator having part numbers (P/Ns) 8489-5, 8489-6, 8489-7, and 8489-7R.
Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
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