Inspections Find Possible Fuselage Cracking And Loose Rivets

The FAA has released a Special Airworthiness Information Bulletin (SAIB) following reports of fuselage cracking and possible loose rivets on Bell Model 206L helicopters in an area that currently has no inspection program.

There are multiple reports of cracks found in the fuselage frame/bulkhead of Bell Model 206L helicopters upper area of fuselage station (FS) 145.

The FAA’s Monitor Safety/Analyze Data (MSAD) data contains several reports documenting cracks found in stiffener Part Number 206-033-107-055. The stiffener is located in the upper area of FS 142.7 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 FS 145. 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 is required to inspect the most aft hardware of the pylon support assemblies for the transmission and the forward engine mount fuselage structure. 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. Transport Canada has issued Civil Aviation Safety Alerts (CASA) No. 2019-05 to raise awareness of a potential crack in the fuselage frame/bulkhead going undetected during a scheduled maintenance inspection. The CASA is available here.

The FAA recommends the following for all Bell Model 206L series helicopters:
Each time the left and right hand door assemblies of this SAIB are removed, inspect the entire internal structure of FS 142.7 to FS 155.00 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. A borescope could also be used.
Use the approved Bell Maintenance and Structural Repair Manuals (SRM) for inspecting, repairing and replacing defective parts that are within the scope of authorized maintenance.
For any repairs not included in the SRM, repair in accordance with any FAA approved repair. The FAA will continue to monitor MSAD (SDR) related to this issue and may issue recommended or mandatory corrective action, if necessary.

(Source: FAA. Image from file)

FMI: SAIB