2010-07 · NASA ASRS report 922697
A Technician reports he installed an Elastomeric Tail Rotor Hub and Composite Blade Assembly on a Bell 206 Ranger helicopter. Another Mechanic later informed him the hub assembly should have had a Supplemental Type Certificate (STC) and FAA Form 337 included in the paperwork. A tail skid dampner counterweight was also missing.
I installed a Tail Rotor Blade and Hub Assembly on one of our Bell 206 fleet aircraft. This assembly was built up by our company; Air X; maintenance shop and delivered to our maintenance base for installation. Assembly was ordered by another Air X employee in ZZZ; but I don't know who it was. Assembly was sent with historical service records. In November 2010; an Implementation and Operational Support Team Mechanic was working at our base; where Aircraft X is assigned to; and reported there was no dampner weight installed on the tail skid; and that it was required to be installed when a Lord Elastomeric Hub is used. After talking with our Regional Maintenance Manager and Company District Office Manager; it was discovered this Elastomeric Hub was part of a Lord STC (Supplemental Type Certificate). I didn't know about this and installed the [tail rotor] blade/hub assembly with an FAA Form 337; issued for the Van Horn Composite Blade STC. [There was] no FAA Form 337 [included] with the Lord Elastomeric Hub STC. The blade and hub assembly I removed was also an Elastomeric Hub from a previous installation; built up by our company's Maintenance shop. So without knowledge of an STC requirement [for the Elastomeric Hub]; the tail rotor was replaced as a normal [installation].
Reporter stated two Supplemental Type Certificates (STCs) and two FAA 337 forms should have been included with the Elastomeric Hub and Tail Rotor Composite Blade Assembly sent to him. Instead; only the Tail Rotor Composite Blade Assembly STC and 337 Form had been sent. The standard Bell 206 hub assembly is time limited and was being replaced with a hub that uses Elastomeric parts. Some hub assemblies are rebuilt with metal blades; but still use Elastomeric parts; which can be compared to a car's drive shaft 'U' joint; that is made from synthetic material instead of metal. He uses the same mounting bolts; shims; washers and bushings; but realizes an STC and FAA Form 337 paperwork is required whenever an Elastomeric hub is installed. Reporter stated the composite tail rotor has a scimitar curve near the blade end compared to the Bell constant chord blade with a square end. The balance check he performed on the Tail Rotor Blade Assembly passed after he had installed the hub and rotor even though the dampner weight was missing.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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