Attention:
Owners, operators and maintainers of all Bell Textron Canada Limited (bell) 206 and 427 model helicopters
| File Classification No.: | Z 5000-35 |
|---|---|
| RDIMS No.: | 21001052 |
| Document No.: | CASA 2025-09 |
| Issue No.: | 01 |
| Effective Date: | 2025-07-09 |
Purpose:
The purpose of this Civil Aviation Safety Alert (CASA) is to raise awareness of reported pilot cyclic stick tubes cracking on Bell 407 model helicopters, which are also installed on other Bell model helicopters.
Background:
Bell has received a report of a fractured pilot cyclic stick Part Number (P/N) 206-001-342-101 found while performing the interior and prestart check of the 407 Rotorcraft Flight Manual (RFM). The fracture originated at the upper slotted area near the lower base of the cyclic stick as shown in Figure 1. Further investigation revealed that additional cyclic sticks were found to be cracked from fatigue. Bell has determined that the root cause of the cyclic stick cracking was attributed to excessive force being applied to the cyclic stick during the freedom of movement of the controls and cyclic centering light operation check as part of the interior and prestart check, which resulted in elevated stress at the slotted area, aggravated by the high stress concentration design feature of the upper slotted area.
Figure 1 – Location of the fracture on the pilot cyclic stick tube
Bell has released Alert Service Bulletin (ASB) 407-23-130 to require a one-time detailed inspection and replacement or repair, as applicable, of the cyclic stick tube assembly. Transport Canada mandated this corrective action and a revised RFM procedure in Airworthiness Directive CF-2024-18.
This pilot cyclic stick tube P/N 206-001-342-101 can also be installed on all Bell 206 and 427 model helicopters. Bell found that the excessive applied loads on the cyclic stick are unique to the 407 model; the loads applied on the pilot cyclic stick for the Bell 206 and 427 model helicopters are significantly lower. However, Bell decided to release ASBs for all Bell 206 and 427 model helicopters because of the potential susceptibility to fatigue cracking due to the high stress concentration design feature of the upper slotted area of the pilot cyclic stick tube.
Recommended action:
Transport Canada recommends that owners, operators and maintainers of all Bell 206 and 427 model helicopters carry out the inspection and corrective actions, as required, described in the applicable Bell ASB:
- Bell 206A/B: ASB 206-23-142 Revision A, dated 27 March 2023, or later revisions.
- Bell 206L series: ASB 206L-23-187 Revision A, dated 27 March 2023, or later revisions.
- Bell 427: ASB 427-23-46 Revision A, dated 27 March 2023, or later revisions.
Within Canada, in accordance with the reporting requirement of Part V, subpart 21 (521) of the Canadian Aviation Regulations (CAR), owners, operators and maintainers should submit a Service Difficulty Report (SDR) to Transport Canada for the discovery of each reportable service difficulty. Outside Canada, report any such occurrence in accordance with local reporting requirements.
Contact office:
For more information concerning this issue, contact a Transport Canada Centre; or contact Nafi Dicko-Raynauld, Continuing Airworthiness in Ottawa, by telephone at 1-888-663-3639, or by e-mail at TC.CAWWEBFEEDBACK-retroactionWebMDLN.TC@tc.gc.ca
Original signed by
Jenny Young
Chief, Continuing Airworthiness
National Aircraft Certification
Pilot cyclic stick tube cracking
(PDF, 266 KB)
The Transport Canada Civil Aviation Safety Alert (CASA) is used to convey important safety information and contains recommended action items. The CASA strives to assist the aviation industry's efforts to provide a service with the highest possible degree of safety. The information contained herein is often critical and must be conveyed to the appropriate office in a timely manner. The CASA may be changed or amended should new information become available.