NTSB INVESTIGATION OF BOSTON LOGAN 787 LITHIUM ION BATTERY COMBUSTION / As earlier announced all five members of the NTSB Board held two days of a formal hearing in furtherance of the NTSB’s investigation of the Boston Logan incident. In a brief but noteworthy wrap-up after the second day, NTSB Chairman Herseman made two noteworthy statements: (1) “[W]e do not know the cause of the JAL battery failure”; and (2) the following questions remain “just as pressing” after the two days’ hearings – “[1] how best to certificate emerging technology to ensure safety, and [2] whether the certification process is flexible enough to incorporate new knowledge”.

As I observed in the Comments section a few days ago on this subject, the FAA’s April 19 press release announcing that, “the FAA will issue instructions to operators for making changes to the aircraft and will publish in the Federal Register the final directive that will allow the 787 to return to service with the battery system modifications”. 

And consistent with that the FAA followed up April 26 with an airworthiness directive in the Federal Register reported in this blog here 

Where do the above two developments – the April 26 airworthiness directive and the NTSB’s two days of hearings on April 22 and 23 – leave the flying public? 

1. The NTSB expressly acknowledges that it has reached no conclusion as to the cause of the combustion incidents occurring to the 787 lithium ion battery system, and that the Japan Transport Safety Board had not reached any  conclusion on the matter either (the two incidents occurred with 787’s registered on the Japanese air registry. 

3. In the April 19 press release and the April 26 airworthiness directive at least the FAA does not offer any conclusion on the cause nor does it state any intent to so conclude at any future time. 

4. The FAA in the April 26 airworthiness directive acknowledges the existence of an “unsafe condition” with respect to the 787 lithium ion battery system, and acknowledges the same with respect to its earlier airworthiness directives relating to the matter. 

5. The airworthiness directive is in the form of a final rule: “… [W]e find that notice and opportunity for prior public comment are impracticable and would defeat the Agency’s [FAA’s] regulatory objective, and that good cause exists for making this amendment [i.e., airworthiness directive that supersedes a prior one, as earlier amended] effective in less than 30 days.” 

6. The airworthiness directive, although acknowledging (as all airworthiness directives do) a “dangerous condition”, does not assert that such airworthiness directive will render the aircraft system to be actually safe: In the FAA’s words, the airworthiness directive “will address the unsafe condition”. 

7. “The purpose of the [airworthiness directive] is to allow the aircraft to return to service as soon as possible by mandating a modification that will address the unsafe condition.” 

The above summary is based upon my own careful reading and re-reading of FAA and NTSB statements of the past 10 days. In particular note: 

1. The disconnect between the NTSB’s own reservation of judgment following its April 22 and 23 investigative hearing versus what amounts to an FAA green light to fly the 787 without concluding what the problem was in the first place is set forth in the official documents. 

2. Also note the FAA’s statement that the decision to issue this airworthiness directive and allow the 787 to operate – without having concluded what caused the combustion incidents – is a function of commercial factors combustion (“The purpose of this AD is to allow the aircraft to return to service as soon as possible by mandating a modification that will address the unsafe condition.”).