As of March 2017, the success rate of H-IIA launch vehicle, the Japan's flagship rocket, is 97%; 32 out of 33 launches were successful and accomplished the mission.
The project manager of H-IIA No. 6, the only failure of H-IIA, was Mr. Yukimoto Nimura, the current mission director, Executive Officer and Fellow.
H-IIA No. 6 launch, which was reported as "a failure to shake the confidence in Japan's aerospace technology, failed on November 29, 2003. The H-IIA No. 7 with modified design, however, was successfully launched only 15 months later. Since then the H-IIA program is enjoying the great track record and its reliability is highly regarded globally. Combined with the H-IIB launch vehicles that have a 100% success rate, they established a record of 33 consecutive successful launches. The detrimental failure resulted in significant organization restructuring. Mr. Nimura talks in his interview about the journey to the success of H-IIA No. 7 where program members worked as one with "Return to Flight" as the mantra.
What changed between H-IIA No. 6 and No. 7
It was when production of H-IIA, which was developed to improve cost competitiveness by potentially using cheaper non-Japanese parts while further enhancing reliability was becoming stable. Its predecessor H-II was a pure Japanese-bred costly launch vehicle. At the same time the development of H-IIA 204 (H-IIA No. 11) that changed the solid rocket booster (SRB-A) configuration from 2 to 4 was entering into the busiest phase and the development of H-IIB that had a mission to launch the ISS supply ship, which was too heavy for H-IIA, had just started. The development environment was confusing.
Nimura: It would have been simple and easy to launch H-IIA rockets but we had to deal with H-IIA 204 and H-IIB at the same time. They appeared quite similar but had subtle differences. The engineering field was confused with these similar but different vehicles. Because of that, I paid extra attention to inspection and tests.
Despite this effort, one of the SRB-A of H-IIA No. 6 did not separate. Losing the possibility of reaching the expected altitude, a command was sent from the ground and H-IIA No. 6 was self-destructed about 11 minutes after lift off.
On February 26, 2005, 15 months after the launch failure, H-IIA No. 7 carrying the Multi-Purpose Transport Satellite "Himawari No. 6" successfully completed its mission although its launched was delayed due to weather.
There was great a transformation in Japan's rocket production during the 15 months.
NASDA (later JAXA) was responsible for development of launch vehicles up to H-IIA No. 6; underneath of NASDA there were Mitsubishi Heavy Industry, IHI Aerospace, and Kawasaki Heavy Industry as subcontractors. Each of them manufactured components assigned to them, which were assembled by NASDA at the end.
The scope of the "H-IIA Rocket Overhaul" project, which started to learn lessons from the H-IIA No. 6 failure included, included the root cause analysis of SRB-A separation failure as well as enhancement the development framework and review of the overall design process. When venders are in the same tier, they could check only what they did. This structure was lacking end-to-end review capability. In the "Overhaul" project, Mitsubishi Heavy Industry was granted a position by NASDA, which allowed it to review other venders' designs to a certain degree in support of NASDA's activities.
Venders were reluctant to disclose proprietary technology and design know-how to Mitsubishi. It was a big challenge for Mitsubishi to have information disclosed to them.
Return-to-Flight as the mantra
H-IIA rocket development engineers shared a common desire and goal. It was to recover from the H-IIA No. 6 failure and resume launch activities as quickly as possible.
Mr. Nimura, then, called on venders, asking for their cooperation with "Return-to-flight" as the mantra.
Nimura: I was focusing on making the entire system better then. "We want you to disclose what we need; in turn we will show you the data we have, too." That is how I called on them in attempt to get their cooperation. I also told them, "Do not worry. We will not be able to make it by looking at your technology." (Laughter)
Of course, I did not force them to share what they could not. "Without the knowledge, we would not be able to make a recommendation. Please briefly show us only that part." I kept asking them.
In the end, all venders agreed to disclose necessary information. The structure in which Mitsubishi Heavy Industry reviewed the end-to-end process under the leadership of NASDA was formed within a few months.
In the project, not only the process was checked to find issues but the corrective actions had to be incorporated in design and products. "I don't remember exactly how long it took but I tried to do it fairly timely," says Mr. Nimura.
A key lesson learned in the project was optimization of component-level design did not necessarily make the entire system better. Mitsubishi proposed standard improvement points. With a shared strategy, venders' solutions were better standardized and results were better aligned. The results of the review exercise were boiled down to dozens of design changes despite a very large number of components and parts.
Nimura: It was wonderful that an environment where engineers of different companies could talk to each other was created. Communication became much better than when components that had been made independent of each other were gathered and put together.
Mr. Nimura who played the central role at Mitsubishi in the "Review" project treasured "know why" that was inspired from "know how."
Why "know how" is not good enough? What does "know why" mean?
We will talk about "know why" which is critical in manufacturing in the next article.