AD 2023-11-04 Airworthiness Directives; Bombardier, Inc., Airplanes

Models named: BD-100-1A10. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Bombardier, Inc., Model BD-100-1A10 airplanes, certificated in any category, having serial number 20003 and subsequent.

Comply with this AD within the compliance times specified, unless already done.

Within 60 months after the effective date of this AD, check the airplane maintenance records or do a visual check to determine the part and serial numbers of the HSTA. (1) If the part number is C47100-005: No further action is required by this paragraph. (2) If the part number is C47100-004 and the serial number ends with the suffix-K: No further action is required by this paragraph. (3) If the serial number is listed in the table referred to in paragraph 2.B.(4) of the Accomplishment Instructions of the applicable Bombardier service bulletin identified in figure 1 to paragraph (g)(3) of this AD: Within 60 months from the effective date of this AD, inspect the HSTA no-back mechanism pawls in accordance with paragraph 2.C. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. (i) If one or more pawls are not correctly installed: Before further flight, replace the HSTA in accordance with paragraph 2.E. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. (ii) If all the pawls are correctly installed, re-identify and test the HSTA, and do all applicable corrective actions, in accordance with paragraphs 2.C.(4) and 2.F. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. Figure 1 to Paragraph ( g )(3)—Applicable Service Information Airplane model Applicable bombardier service bulletin BD-100-1A10 (CH300 marketing) 100-27-20, Revision 01, dated December 1, 2020. BD-100-1A10 (CH 350 marketing) 350-27-009, Revision 01, dated December 1, 2020. (4) If the serial number is listed in the table referred to in paragraph 2.B.(5) of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD: Within 60 months from the effective date of this AD, add a modification plate to the HSTA in accordance with paragraph 2.D. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. (5) If the records check is inconclusive, or if a visual check instead of a records check of the HSTA was accomplished: Within 60 months from the effective date of this AD, verify the part numbers and serial numbers of the HSTA, and verify the modification plate, in accordance with paragraph 2.B. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. (i) If the HSTA has part number (P/N) C47100-005: No further action is required by this paragraph. (ii) If the HSTA has P/N C47100-004 and a serial number that ends with the suffix-K, or if the modification plate contains “SB C47100-27-02” or “SB C47100-27-03”: No further action is required by this paragraph. (iii) If the serial number is listed in the table referred to in paragraph 2.B.(4) of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD: Within 60 months from the effective date of this AD, inspect the HSTA no-back mechanism pawls in accordance with paragraph 2.C. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. (A) If one or more pawls are not correctly installed, before further flight, replace the HSTA in accordance with Paragraph 2.E. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. (B) If all the pawls are correctly installed, re-identify and test the HSTA, and do all applicable corrective actions, in accordance with paragraphs 2.C.(4) and 2.F. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD. (iv) If the serial number is listed in the table referred to in paragraph 2.B.(5) of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD: Within 60 months from the effective date of this AD, add a modification plate to the HSTA in accordance with paragraph 2.D. of the Accomplishment Instructions of the applicable service bulletin identified in figure 1 to paragraph (g)(3) of this AD.

This AD was prompted by a report that a design deficiency was discovered which could allow a no-back pawl to be incorrectly installed in a horizontal stabilizer trim actuator (HSTA). The FAA is issuing this AD to address incorrectly installed no-back pawls. The unsafe condition, if not addressed, could result in a non-functioning no-back mechanism, which, in combination with loss of or degraded HSTA motor brake assembly (MBA) braking capability, could lead to a loss of control of the airplane.

None.