Investigators on the ground near the crash site of the Ethiopian Airlines 737 Max found the plane’s jackscrew, a part that moves the horizontal tail of the aircraft, and it indicates that the tail was in an unusual position, according to an aviation safety consultant briefed on the findings.

The consultant, John Cox, chief executive of Safety Operating Systems and formerly the top safety official for the Air Line Pilots Association, said that Boeing’s new flight control system on the Max — implicated in the preliminary investigation into the earlier crash of a Lion Air jet in Indonesia — is one of several possible systems that could explain the unusual deflection in the horizontal tail, a control surface that swivels to pitch the plane’s nose up or down.

This, along with evidence from a new satellite-based system that tracked the flight data and revealed similar trajectories on the two flights, is what finally led the Federal Aviation Administration to ground the Max on Wednesday, following regulators around the world.

Boeing plans to continue production and keep its 737 supply chain and assembly lines moving, even as investigators continue to look into the causes of both crashes that together killed 350 people and led governments across the globe to ground the aircraft.

“There has been no change in the production rate at this time,” Boeing said in a statement.

The FAA briefed lawmakers on Thursday about Boeing’s plans to develop a software patch for the suspect flight control system, providing the most detailed look yet at the company’s efforts to get the plane back in the air.

The timeline for that fix — which would still have to win FAA approval — means the planes are unlikely to be cleared to fly any earlier than toward the end of next month.

In an interview Thursday, Rep. Rick Larsen, chairman of the House Aviation Subcommittee, said the FAA expects to approve a software fix for the new flight control system — called MCAS (Maneuvering Characteristics Augmentation System) — by the end of this month so that Boeing can begin to deploy it in the worldwide fleet of nearly 400 Maxs in April.

He said Boeing will also provide more training materials for pilots on the system and on the changes made to how it operates.

In a less optimistic analysis, Ronald Epstein, an aviation industry financial analyst with Bank of America, told investors it could take Boeing three to six months to fix the troubled aircraft.

The worldwide grounding, meanwhile, has left airlines scrambling to meet their schedules with other planes.

The new flight control system on the Max, the MCAS, was added so that the new plane would behave and feel the same to pilots as the older model 737s.

It was necessary because the new model’s bigger engines, positioned farther forward on the wings, changed the plane’s lift characteristics in a high-speed stall situation.

MCAS is designed to swivel the horizontal tail so as to push the plane’s nose down automatically, without pilot input, if a sensor on the fuselage indicates the nose relative to the air flow is at too high an angle — the Angle of Attack.

Boeing has been working on a fix since soon after the Lion Air crash in October, when a preliminary investigation indicated that a false reading on the AOA sensor triggered MCAS to repeatedly push the plane’s nose down and forced the Lion Air pilots into a losing struggle to pull it up again.