The Cicaré 7T/B/BT mandatory service bulletin (BSC007) for the general stabiliser support assembly provided limited guidance for disassembly of the manufactured component and did not stipulate a compliance period within which to perform the inspection nor provide consideration for repeat inspections. This potentially reduced the opportunity to detect the presence of crack initiation and growth in the stabiliser support assembly.
The ATSB is satisfied that, with the inclusion of BSC007 in the maintenance manual and a clear direction to inspect the stabiliser assembly every 100 hours, cracking in this location will likely be identified prior to failure. Additionally, Cicaré have redesigned the component, and all new Cicaré 7 series helicopters will be fitted with the new design, which is also available for retrofit on earlier helicopters.
Operating a helicopter within the stated design intent and limitations is essential for safe conduct of flight. The ATSB advises owners/operators of amateur-built experimental aircraft to be fully aware of the risks associated with this category of aircraft and that operation outside the limitations prescribed by the manufacturer, such as the addition of unapproved modifications and use for mustering operations, can produce unintended stresses on the airframe leading to premature failure of components.
AO-2015-089-SAN-014: Are you operating your amateur-built helicopter as designed?
Cicaré have advised that they are intending to release a revision to the Pilot’s Operating Handbook at the end of January 2020, which will indicate that the helicopters are not intended or recommended for aerial work, particularly mustering operations, which can cause a significant increase of loads and affect the fatigue life.
BSC007 Revision 2 was released on 30 September 2015, which included a description of how to remove the vertical and horizontal fins to perform the inspection. It referred to the same inspection procedure as Revision 1. However, both versions did not include an initial or recurrent time period within which to conduct the inspection.
The inspection was incorporated into their maintenance manual and scheduled inspection table, and is required every 100 hours’ time-in-service. Cicaré advised that they continue to monitor the ongoing non-destructive inspections of the assembly, and that as of November 2019, no other cracks have been found.
Cicaré have also advised that the stabiliser assembly was redesigned at the end of 2015. The new stabiliser was originally designed for the Cicaré CH-8 series helicopter, as the original Cicaré 7 series stabiliser was too small for a two (side-by-side) seat helicopter, such as the CH-8. Cicaré also advised that they wanted to improve the structural and aerodynamic characteristics, and improve the production process. Following design, static testing and flight testing on the CH-8, the new design was tested on the Cicaré 7 series and Cicaré 12 with positive results. All new helicopters, except the SVH4 trainer, utilise the new design and it is also available for retrofit on earlier Cicaré 7 series models.
BSC013, T-type stabilizer installation, released on 18 March 2019, provided information on why and how to perform the installation. If the new stabiliser was installed, the 100 hourly inspection, in accordance with BSC007, was no longer required. Cicaré have advised that they are continuing to monitor in‑service behaviour of the new stabiliser in the Cicaré CH-8 every 100 hours, as part of the certification process and internal tracking of the in-service life of the components The ATSB has been advised that at least two operators in Australia have installed the new design.
