Airworthiness Directive · Amendment 39-16272 · Flight controls
Bombardier, Inc. Model DHC-8-400 Series Airplanes
This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes; certificated in any category, that are equipped with Thales angle of attack (AOA) vanes having part number (P/N) C16177AC.
We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 250 flight hours after the effective date of this AD: Do an inspection to determine the serial number of the AOA sensors installed on the airplane, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009. A review of airplane maintenance records is acceptable in lieu of this inspection if the serial number of the AOA sensors can be conclusively determined from that review.
(1) If neither serial number is specified in paragraph 1.A., Table 1, of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009, do the actions required by paragraph (h) of this AD.
(2) If the serial numbers of both AOA sensors are specified in paragraph 1.A., Table 1, of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009, and both serial numbers have suffix “B,” do the actions required by paragraph (h) of this AD.
(3) If the serial numbers of both AOA sensors are specified in paragraph 1.A., Table 1, of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009, do the actions required by either paragraph (g)(3)(i) or (g)(3)(ii) of this AD.
(i) Before further flight, replace the AOA sensors with new or serviceable sensors, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009.
(ii) Before further flight, replace one of the two AOA sensors with a new or serviceable sensor, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009. Replace the remaining sensor with a new or serviceable sensor within 750 flight hours after the inspection required by paragraph (g) of this AD.
(4) If only one of the serial numbers of the AOA sensors is specified in paragraph 1.A., Table 1, of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009, replace that sensor with a new or serviceable sensor within 750 flight hours after the inspection required by paragraph (g) of this AD.
(h) At the applicable compliance time specified in Table 1 of this AD: Measure the inrush current of the AOA vane, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A84-27-46, dated October 20, 2009.
(1) If, during any measurement required by paragraph (h) of this AD, an AOA vane is found to have an inrush current less than or equal to 1.6 amps, before further flight, replace the vane with a new or serviceable vane, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A84-27-46, dated October 20, 2009. Repeat the measurement of the newly installed vane within 2,000 flight hours after replacement.
(2) If, during any measurement required by paragraph (h) of this AD, an AOA vane is found to have an inrush current greater than 1.6 amps, repeat the measurement of the vane at the applicable compliance time specified in Table 2 of this AD.
| For any AOA vane that, as of the effective date of this AD, has accumulated— | Do the initial inrush current measurement— |
|---|---|
| Less than 5,000 total flight hours | Before the AOA vane has accumulated 5,900 total flight hours. |
| 5,000 or more total flight hours, but less than 6,000 total flight hours | Within 900 flight hours after the effective date of this AD, or before the AOA vane has accumulated 6,500 total flight hours, whichever occurs first. |
| 6,000 or more total flight hours | Within 500 flight hours after the effective date of this AD. |
| If the last inrush current measurement of the serviceable AOA transducer is— | Then repeat the measurement— |
|---|---|
| More than 1.60 amps, but less than or equal to 1.70 amps | Within 1,000 flight hours after the last inrush current measurement of the serviceable AOA transducer. |
| More than 1.70 amps | Within 2,000 flight hours after the last inrush current measurement of the serviceable AOA transducer. |
(i) As of the effective date of this AD, no person may install, on any airplane, an AOA sensor having P/N C16177AC with any serial number specified in paragraph 1.A., Table 1, of Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009, unless the sensor has been inspected in accordance with this AD and unless the serial number has a suffix “B.”
Note 1: This AD differs from the MCAI and/or service information as follows: (1) Canadian Airworthiness Directive CF-2010-05, dated February 2, 2010, requires an inspection to determine the serial number of the AOA vanes installed on the airplane. However, for clarification, we are requiring an inspection to determine the serial number of the AOA sensors (which are part of the vane), as specified in Bombardier Alert Service Bulletin A84-27-51, dated December 22, 2009. (2) Canadian Airworthiness Directive CF-2010-05, dated February 2, 2010, states that an airplane may be dispatched with one serviceable unit for a maximum of 1,000 flight hours. However, paragraph (g)(3)(ii) of this AD allows an airplane to be dispatched with one serviceable unit for a maximum of 750 flight hours. This difference has been coordinated with Transport Canada Civil Aviation (TCCA). (3) Canadian Airworthiness Directive CF-2010-05, dated February 2, 2010, states that if only one of the serial numbers of the affected AOA sensors is found, replace that sensor with a new or serviceable sensor within 1,000 flight hours. However, paragraph (g)(4) of this AD requires replacement with a new or serviceable sensor within 750 flight hours. This difference has been coordinated with TCCA.
