Bell 206L Cracks in Fuselage - Civil Aviation Safety Alerts (CASA) No. 2019-05


Owners, operators and maintainers of Bell model 206L series helicopters

File Classification No. : Z 5000-35
RDIMS No. : 15708454
Document No. : CASA 2019-05
Issue No. : 02
Effective Date: 2019-09-09


The purpose of this Civil Aviation Safety Alert (CASA) is to raise awareness of a potential crack in the fuselage frame/bulkhead going undetected during a scheduled maintenance inspection.

This revision of CASA 2019-05 is issued to correct an error in the 3rd paragraph of the Background and under Item 1 of the Recommended Action section of the French version of the original CASA.


Multiple reports exist where cracks were found in the fuselage frame/bulkhead of Bell model 206L helicopters upper area of fuselage station (FS) 145.

Transport Canada (TC) was notified of several occurrences of cracks found in stiffener Part Number 206-033-107-055. The stiffener is located in the upper area of FS142.7 where the aft cabin bulkhead and the bulkhead for the aft passenger seat come together.

Further investigation, including reports from the Service Difficulty Report (SDR) database, revealed additional occurrences of cracks in the area of FS145. The reported cracks were found by visual inspection and were not limited exclusively to the stiffener. This area can be highly loaded and could be subjected to movement. As a result of the movement, it is not uncommon to find the rivets in this area smoking or working and in need of replacement. Over time, the loose rivets could result in cracking of the fuselage structure.

During parts of the progressive inspection, opening of the door assemblies identified in figure 1 (item 24, 24A & 24B) is required, to inspect the most aft hardware of the pylon support assemblies for the transmission and the forward engine mount fuselage structure.



Figure 1.

However, there are currently no specific Service Bulletins or Notices to inspect this area. Access to conduct a thorough inspection can also be limited by the size of the opening. The Bell 206L Maintenance Manual and Structural Repair Manual do not include specific damage assessment criteria or repairs for this area.

Recommended action:

TC recommends the following for all Bell model 206L series helicopters:

  1. Each time the left and right hand door assemblies identified in Figure 1 (item 24, 24A & 24B) of this CASA are removed, conduct a thorough inspection covering the entire internal structure of FS142.7 to FS155.00 for smoking and working rivets and for cracks. For areas with limited access, the use of a mirror and flashlight as an aid in the visual inspection is recommended.
  2. Use the approved Bell Maintenance and Structural Repair Manuals for inspecting, repairing and the replacement of the defective parts that are within the scope of authorized maintenance.
  3. Contact Bell for damage assessment and repair instructions for cracks that are not within the approved criteria.
  4. Submit an SDR for each reportable service difficulty to TC in accordance with the reporting requirement of Part V, subpart 21 (521) of the Canadian Aviation Regulation (CAR). For all other rotorcraft not affected by the CAR, report defects in accordance with local reporting requirements.

TC will continue to monitor events related to this issue and will issue recommended or mandatory corrective action, as necessary.

Contact office:

For more information concerning this issue, contact a Transport Canada Centre; or contact Jody Bird, Continuing Airworthiness in Ottawa, by telephone at 1-888-663-3639, facsimile 613-996-9178 or e-mail at

Original signed by

Rémy Knoerr
Chief, Continuing Airworthiness
National Aircraft Certification

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.