Bombardier is scrambling to develop new production plans for the midsize Learjet 85 after dropping troubled Grob as the supplier of the airplane’s composite fuselage.

The Canadian manufacturer last month terminated its contract for the Learjet 85 fuselage in the wake of Grob’s German affiliate filing for insolvency.

In a prepared statement, Steve Ridolfi, president of Bombardier Business Aircraft, noted, “Given the uncertainty surrounding Grob’s insolvency, Learjet has decided to terminate its agreement with Grob Aerospace. Bombardier Aerospace is taking decisive action and this decision reflects our strong commitment to both the Learjet 85 aircraft program and to a growing number of leading business jet customers worldwide who have selected this exciting, all-new midsize business jet.”

Grob Aerospace GmbH filed for insolvency in Germany after its main source of capital suddenly withdrew financial support for its SPn light business jet program.

Grob CEO Niall Olver said that the undisclosed investor had pulled out due to delays in the SPn certification program and resulting increases in the amount of money required to get the aircraft into service.

Bombardier said it is assuming complete responsibility for the detail design and manufacturing of all primary and secondary structures for the eight-passenger Learjet 85.

Grob issued the following statement in response to Bombardier’s decision: “Whilst this outcome is regrettable, it is a matter of fact that Bombardier needs to take whatever measures they [sic] deem necessary in order to protect the time line of their program. The parties have agreed to cooperate and to jointly remove the Bombardier program from the Tussenhausen-Mattsies [Germany] facility.”

As of last week Bombardier was still formulating specifics for development of the Learjet 85 without Grob. The original plan called for all of the structures for the entire first aircraft to be fabricated by Grob, with some production gradually transferred to Bombardier on subsequent aircraft.

Bombardier originally planned to transfer that work to a production facility in Mexico, but those plans are now uncertain.

“We are going to control development,” a Bombardier spokeswoman said, “but we haven’t determined where exactly things will be done, other than that they will be at a Bombardier site.”

Dropping Grob from the project may also mean that the composite technology for the Learjet 85 will be changed from a low-pressure, hand lay-up system to composites pre-impregnated (pre-preg) with resins that are then heat-cured.

“We haven’t finalized the details yet,” the Bombardier spokeswoman said, “but we hope to share them at NBAA.” Bombardier declined a request for a phone interview with a senior company executive to discuss the program. The company currently has 90 letters of intent and 45 firm orders for the $17.2 million (2008 $) Learjet 85. Deliveries are scheduled to begin in 2012.