There's a landing gear shear pin AD reported elsewhere in this issue; but it's important to note that the FAA on Wednesday issued an emergency AD that grounds the entire US fleet of Learjet 45 business aircraft. This is no 'shear pin AD.'

The horizontal stabilizer is the culprit. More precisely, a screw and nut assembly in the control of the elevator is the culprit. If this sounds familiar, it may be because Lear 45 operators just replaced those faulty assemblies this Spring.

There are well over 200 of these birds flying important people around; this again-defined horizontal stabilizer problem is keeping them on the ground, until repairs are made. The parts supply should start to perk up in about a week or two; in the meantime, the 173 or so of the fast birds in the USA are stuck to the ground.

In March, a faulty screw and nut assembly in the horizontal stabilizer control was determined to have caused an unexplained vibration in a Lear 45. Though the crew landed that machine without incident, investigation showed a dangerous problem. The Emergency AD was issued March 20, and reported through the regular system in late April. Spares were issued immediately -- but it now looks like the spares were also defective.

How long down?

Just how long the 45s will be sitting, "is a function of how quickly the FAA certifies the part and we get them to the airplanes, but we hope that will be done very quickly," Bombardier Learjet spokesman David Franson said, from Wichita (KS).

FMI: www.bombardier.com