DAVID LEARMOUNT / LONDON
FAA insists on component change as manufacturer turns to fractionals for assistance
Bombardier has been forced to help owners of around 200 Learjet 45 business jets to make alternative transport arrangements while it replaces a crucial control system component that the US Federal Aviation Administration insists is changed before the type can fly again.
No approved replacement part exists, and the issue appears to hinge on the FAA's dissatisfaction with quality control in the part supplier's manufacturing process.
The effective grounding has hit individual corporate Learjet 45 owners particularly hard, and Bombardier has offered them subsidised aircraft usage rates with fractional ownership operators Bombardier Skyjet in North America and Bombardier Flexjet in Europe and Asia.
UK Learjet 45 operator Gold Air International managing director Will Curtis says that as his company is a mixed fleet operator it has been able to use its Raytheon Hawkers instead, but he is nevertheless negotiating compensation from Bombardier for the effect on business of grounding its five Learjet 45s.
The FAA's scathing airworthiness directive (AD) has shocked Bombardier. The part concerned is the horizontal stabiliser actuator assembly (HSAA), the main component of which is a screwjack that varies the angle of stabiliser incidence to provide pitch trim.
The FAA issued an AD in March requiring fleet-wide replacement of the HSAA, after the component's fracture on a Learjet 45 leading to "severe vibration followed by a rapid nose-down pitch change". The AD says this "could lead to loss of control of the aeroplane".
The replacement was carried out, but the FAA says in its newly issued AD that it is not satisfied with the replacement HSAA, saying: "Although the [new HSAA] is an improvement on the [original part], it was not manufactured per the type design data."
It explains that the HSAA remains vulnerable to a "brittle fracture" similar to that which caused the pitch-down incident. The agency explains it found that "quality controls over the production of these parts were so deficient that we do not have confidence that the aeroplane can be operated safely for any period of time".
Bombardier and the HSAA vendor, MPC Products of Skokie, Illinois, say that this week they will present the FAA with a "data pack" on the manufacturing process that will convince the agency that quality controls were compliant with requirements.
Source: Flight International
