A former Boeing official who was subpoeaned to testify about his role in the development of the 737 Max has refused to provide documents sought by federal prosecutors, according to the Seattle Times, citing his Fifth Amendment right against forcible self-incrimination.
Mark Forkner who was Boeing’s chief technical pilot on the 737 Max project during the development of the plane, was responding to a grand jury subpoena. The US Justice Department is investigating two fatal crashes of the Boeing jet, and is looking into the design and certification of the plane, according to a person familiar with the matter cited by the Seattle Times.
The Fifth Amendment provides a legal right that can be invoked by a person in order to avoid testifying under oath. Because the amendment is used to avoid being put in a situation where one would have to testify about something that would be self-incriminating, it can sometimes be seen by outsiders as an implicit admission of guilt, although that is not always the case.
It is less common to invoke the Fifth to resist a subpoena for documents or evidence. According to legal experts, its use by Forkner could simply suggest a legal manuever between Boeing’s attorneys and prosecutors.
Forkner left Boeing in 2018, according to his LinkedIn page, and is currently a first officer flying for Southwest Airlines.
The Justice Department’s investigation into the two crashes, which occurred Oct. 29, 2018, in Indonesia, and March 10, 2019, in Ethiopia, is a wide-ranging exploration into the development of the plane. The investigation has also grown to include records related to the production of a different plane — the 787 — at Boeing’s Charleston, South Carolina plant, although it is not clear whether those records have anything to do with the 737 Max.
Preliminary reports into the two crashes that led to the grounding — Lion Air Flight 610 and Ethiopian Airlines Flight 302 — indicate that an automated system erroneously engaged and forced the planes’ noses to point down due to a problem with the design of the system’s software. Pilots were unable to regain control of the aircraft.
The system engaged because it could be activated by a single sensor reading — in both crashes, the sensors are suspected of having failed, sending erroneous data to the flight computer and, without a redundant check in place, triggering the automated system.
Grounded Boeing 737 MAX 8 aircraft in China following the crash of Ethiopian Airlines Flight 302.
The automated system, the Maneuvering Characteristics Augmentation System (MCAS), was designed to compensate for the fact that the 737 Max has larger engines than previous 737 generations. The larger engines could cause the plane’s nose to tip upward, leading to a stall — in that situation, MCAS could automatically point the nose downward to negate the effect of the engine size.
The plane has been grounded worldwide since the days following the second crash, as Boeing prepared a software fix to prevent similar incidents. The fix is expected to be approved, and the planes back in the air, by the end of this year or early 2020.
During the certification process, Forkner recommended that MCAS not be included in the pilots manual, according to previous reporting, since it was intended to operate in the background as part of the flight-control system, according to previous reporting.
This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.