{"id":"F2006L00756","name":"AD/DHC-8/114 - Pitch Trim Control","slug":"ad-dhc-8-114-pitch-trim-control","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":136779,"registerId":"commonwealth-F2006L00756-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bombardier (Boeing Canada/De Havilland) ","sectionType":"division","heading":"Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes","content":"### Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\n| AD/DHC-8/114 | Pitch Trim Control | 4/2006 |\n| ------------ | ------------------ | ------ |\n\n| Applicability: | DHC-8 Models 400, 401 and 402 aeroplanes, serial numbers (S/N) 4001 through 4065.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. For aeroplanes S/N 4001 through 4058 - If not previously accomplished, incorporate Modsum 4-113405 by replacing/reworking FGM1 and FGM 2 P/N C12429AA06 with/to FGM P/N C12429AA07 and perform a Return to Service Procedure. Bombardier Service Bulletin (SB) 84-22-04 Auto Pilot - Flight Guidance Module (FGM) - Introduction of Software V666 - Modsum 4-113405 dated 29 November 2001, or later revisions, approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructions for incorporating Modsum 4-113405.                  |\n|                | Note 1: As an interim procedure, until such time as Modsum 4-113405 is implemented, the procedure detailed in Bombardier Service Letter (SL)DH8-400-SL-22-001D dated 8 November 2001 can be used as an approved maintenance procedure to confirm that the AP pitch trim function is serviceable and to restore use of the auto pilot following an autopilot pitch trim failure. This autopilot pitch trim failure is characterized by an “AP PITCH TRIM FAIL” message on the PFD, followed by an “AUTO TRIM FAIL” message after the AP has been manually disengaged.    |\n|                | 2. For aeroplanes S/N 4001 through 4065 - If not previously accomplished, incorporate Modsum 4-113392 by removing Flight Control Electronic Control Units (FCECU) that have either Part Number (P/N) 398500-1001 or P/N398500-1003 and replacing with FCECU P/N 398500-1005. Bombardier (SB) 84-27-14 Flight Controls - Flight Control Electronic Control Unit Upgrade - Modsum 4-113392 dated 16 January 2002, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada, provides approved instructions for replacing the affected FCECUs. |\n|                | Note 2: As an interim procedure, until such time as Modsum 4-113392 is incorporated, the procedure detailed in Bombardier SL DH8-400-SL-27-003 dated 22 May 2001 can be used as an approved maintenance procedure to confirm that the pitch trim system is serviceable following loss of manual pitch trim. This pitch trim failure is characterized by illumination of the “PITCH TRIM” Caution Light and concurrent loss of pitch trim function, during a manual pitch trim input by the flight crew.                                                                 |\n\n|             | Note 3: Transport Canada AD CF-2002-25 refers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | For Requirements 1 and 2 - Within 30 days after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n|             | This Airworthiness Directive becomes effective on 13 April 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| Background: | Transport Canada has advised that two unrelated but recurring malfunctions have been identified with the pitch trim system. The first malfunction involves loss of the autopilot pitch trim, which then requires that the autopilot be disengaged and the aircraft flown manually. With the second malfunction, loss of manual pitch trim can occur due to the pitch trim system being disabled by the monitoring/modelling circuitry in the FCECU. These pitch trim system malfunctions can, under adverse conditions, significantly increase flight crew workload. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n2 March 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/114","sectionType":"part","heading":"AD/DHC-8/114","content":"## AD/DHC-8/114","sortOrder":1},{"sectionNumber":"Pitch Trim Control","sectionType":"part","heading":"Pitch Trim Control","content":"## Pitch Trim Control","sortOrder":2},{"sectionNumber":"4/2006","sectionType":"part","heading":"4/2006","content":"## 4/2006","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a focused, narrow scope — addressing two specific technical defects in a defined aircraft fleet. It has not expanded beyond its original safety purpose."},"complexity_factors":["Technical aviation terminology throughout (Modsums, Part Numbers, Service Bulletins, Flight Control Electronic Control Units)","Two separate requirements with different serial number ranges (4001-4058 vs 4001-4065)","Cross-references to external documents (Bombardier Service Bulletins and Service Letters, plus a Transport Canada AD)","Interim procedures allowed as temporary alternatives to permanent modifications","Specific part number substitutions required (P/N C12429AA06 to P/N C12429AA07, and P/N 398500-1001/1003 to P/N 398500-1005)","Conditional language ('If not previously accomplished') indicating potential prior compliance"],"plain_english_summary":"This CASA Airworthiness Directive mandates repairs for two pitch‑trim failures on Bombardier DHC‑8‑400/Q400 aircraft (S/N 4001–4065, 65 aircraft). It requires a Flight Guidance Module software update to address autopilot pitch‑trim failure and replacement of Flight Control Electronic Control Units to fix manual‑trim loss. The measures are mandatory (compliance within 30 days of 13 Apr 2006); temporary preflight procedures may be used until permanent fixes are done."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive applies to DHC‑8 Models 400/401/402 with specified serial numbers and prescribes two targeted corrective actions (software/module update and FCECU replacement) to address identified pitch‑trim failures. The text does not expand or narrow that applicability beyond the stated serial‑number ranges or the two corrective measures; it instead cross‑references related Transport Canada and Bombardier service documents for implementation details."},"complexity_factors":["Technical dual fixes: a software/module change (FGM software V666, Modsum 4-113405) plus a hardware replacement (FCECU to P/N 398500-1005, Modsum 4-113392) (Requirement 1 & 2).","Serial-number specific applicability (S/N 4001–4058 vs 4001–4065) requires fleet tracking and differentiated work scopes (Applicability; Requirement 1 & 2).","Mandatory returns-to-service and adoption of manufacturer service bulletins or Transport Canada–approved revisions impose procedural compliance and recordkeeping (Requirement 1 reference to SB 84-22-04; Requirement 2 reference to SB 84-27-14).","Interim maintenance procedures are allowed but conditional on specified Bombardier service letters, creating a two-path compliance regime (Notes 1 & 2).","Short compliance window (30 days) concentrates scheduling and resource pressure on operators and maintenance organisations (Compliance).","Regulatory interdependence: references to Transport Canada AD CF-2002-25 and requirement for approval by the Chief, Continuing Airworthiness, Transport Canada add multi-jurisdictional coordination and potential approval delays (Note 3; Requirement approvals).","Operational risk context: two distinct failure modes (autopilot trim vs manual trim loss) mean diagnostics, testing and verification steps may differ and complicate maintenance planning (Background)."],"plain_english_summary":"This directive mandates specific software and hardware changes to the pitch‑trim/autopilot system on Bombardier DHC‑8 Models 400/401/402 (serial numbers 4001–4065): install FGM P/N C12429AA07 (software V666) for S/N 4001–4058 and replace certain FCECU units with P/N 398500‑1005 for S/N 4001–4065. Transport Canada reported two recurring failures—loss of autopilot pitch trim and loss of manual pitch trim—that can increase crew workload; the AD requires compliance within 30 days and permits interim, approved maintenance procedures."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-114-pitch-trim-control","history":"/api/acts/ad-dhc-8-114-pitch-trim-control/history","analysis":"/api/acts/ad-dhc-8-114-pitch-trim-control/analysis","conflicts":"/api/acts/ad-dhc-8-114-pitch-trim-control/conflicts","importantCases":"/api/acts/ad-dhc-8-114-pitch-trim-control/important-cases","documents":"/api/acts/ad-dhc-8-114-pitch-trim-control/documents"}}