Gulfstream-IV Crash, Bedford, MA

You probably have heard of the Gulfstream crash in Bedford, MA last month that killed seven people.

The preliminary NTSB report is out.

Initial review of CVR and FDR data revealed that the airplane's ground roll began about 49 seconds before the end of the CVR recording. The CVR captured callouts of 80 knots, V1, and rotate. After the rotate callout, the CVR captured comments concerning aircraft control. FDR data indicated the airplane reached a maximum speed of 165 knots during the takeoff roll and did not lift off the runway. FDR data further indicated thrust reversers were deployed and wheel brake pressures increased as the airplane decelerated. The FDR data ended about 7 seconds after thrust reverser deployment, with the airplane at about 100 knots. The FDR data did not reveal evidence of any catastrophic engine failures and revealed thrust lever angles consistent with observed engine performance. Review of FDR data parameters associated with the flight control surface positions did not reveal any movement consistent with a flight control check prior to the commencement of the takeoff roll. The flap handle in the cockpit was observed in the 10 degree detent. FDR data indicated a flap setting of 20 degrees during the takeoff attempt.

The airplane was equipped with a mechanical gust lock system, which could be utilized to lock the ailerons and rudder in the neutral position, and the elevator in the down position to protect the control surfaces from wind gusts while parked. A mechanical interlock was incorporated in the gust lock handle mechanism to restrict the movement of the throttle levers to a minimal amount (6-percent) when the gust lock handle was engaged.

The FDR data revealed the elevator control surface position during the taxi and takeoff was consistent with its position if the gust lock was engaged. The gust lock handle, located on the right side of the control pedestal, was found in the forward (OFF) position, and the elevator gust lock latch was found not engaged.

What that all means is that apparently the elevator gust locks had been disengaged in the cockpit but were still somehow engaged. Note that the pilots did not do a "ALL CONTROLS FREE AND CORRECT" check prior to takeoff.

RUMINT on the G-IV is that the pre-engine start checklist calls for disengaging the gust locks prior to engine start. If they are not disengaged and if the hydraulic system is online, then if the pilots unlock the gust locks, the elevator locking pin(s) can be damaged and held in place. If the pilots skip over the item to disengage the gust locks, then they have to shut off the hydraulics, let the pressure bleed off and then disengage the gust locks.

As I said, that's RUMINT. I've got zero PIC time in anything larger than a Navion.

But still, I will bet that when 90% of the pilots read the news reports that the airplane had run off the end of the runway at high speed, the initial thought was that the controls were locked.

It's by no means not the first time this has happened.