The stabilizer is installed at the end of the tail boom at the maximum distance from the helicopter’s center of mass to reduce the harmful inductive rotor effect, and it is intended to improve the pitch balancing and stability of the helicopter. The stabilizer’s structural frame includes a spar, a tail stringer, a tip, ribs and covering. There are two types of stabilizer covering: fabric and metal.
A fabric stabilizer covering was used on the first modifications of the Mi-8/17 helicopters. A significant drawback of this design is the lack of durability of the fabric covering as a result of the low (as compared to metal covering) strength, low resistance to climatic and biological factors, particularly on helicopters operating in marine or tropical climate conditions. This problem was solved by modifying the construction of the stabilizer to use metal instead of fabric covering. The use of the stabilizer with metal covering improved flight safety due to enhanced resistance to mechanical damage (including hail, birds, etc.). The use of metal covering also increased the specified operating life of the stabilizer from 12,000 hours to the specified operating life of the helicopter, and the service life from 25 years to the specified helicopter service life.
The following service bulletins have been issued for the possible replacement of stabilizer 8AT-3100-00-03/04 (with fabric covering) with stabilizer 8AT-3100-00-05/06 on helicopters Mi-8AMT and Mi-171 in operating conditions:
- № АМТ3798-БУ-Г - «Replacement of Stabilizer 8АТ-3100-00-03/04 (with fabric covering) with Stabilizer 8АТ-3100-00-05/06 (with metal covering)».
- АМТ3493-БЭ-Г – «Maintenance Manual – Maintenance Program – Text revision».
- № 171-3798-БУ-БЭ «Replacement of Stabilizer 8АТ-3100-00-03/04 (with fabric covering) with Stabilizer 8АТ-3100-00-05/06 (with metal covering)».