HARRISBURG, Pa. (WHTM) — This is not the first time the National Transportation Safety Board (NTSB) has removed another entity from an investigation. It’s not even the first time this year — the NTSB did that to a steel wheel manufacturer after the Norfolk Southern derailment in East Palestine, Ohio.

But a state government-level regulator?

The NTSB’s history dates to 1967, and no one could confirm definitively that it had never happened. But a spokesman said Tuesday the board’s pipeline experts had “no recollection that NTSB has had an issue with a similar entity” to Pennsylvania’s Public Utilities Commission (PUC), which the NTSB said Monday it had removed from the investigation of the March 24 R.M. Palmer candy factory explosion in West Reading.

“It’s very unusual,” agreed NTSB’s chair from 1994 through 2001 Jim Hall, during a brief telephone interview Tuesday morning.

Hall said the PUC should hand over the documents the NTSB is demanding.

The NTSB said the PUC “violated the terms of the agency’s party agreement” — the agreement that included the PUC in the investigation — “by not providing unredacted inspection and investigation reports of UGI Utilities, Inc., the natural gas pipeline operator whose assets were involved in the gas explosion.”

A former PUC commissioner — Kim Pizzingrilli, who served from 2002 through 2010 — agreed the move was highly unusual but had a different view of what commissioners should do.

“From the press release, obviously, the commission took every step that they thought they could take to cooperate with the federal agency,” Pizzingrilli said. “Each of the five commissioners takes an oath of office when they are nominated and confirmed by the Senate to uphold the laws of the Commonwealth. And in this situation, their opinion is that [providing the documents in question to the NTSB] would have violated Pennsylvania law.”

The PUC is referring to Pennsylvania’s “Confidential Security Information Protection Act,” or CSI, passed in 2006 — the post-9/11 era, when governments were scrambling to prevent sensitive information from getting into the wrong hands.

But is the NTSB really the wrong hands?

A source who works with the utilities and energy industry and requested anonymity said it’s entirely possible the PUC’s commissioners have no philosophical issue with providing the documents — which the source said would likely include “location information” about pipes, interconnections and meters at the factory — but simply believe they would be breaking state law if they were to provide it.

Sure enough, the PUC’s statement said: “Under the current CSI Act there are no exceptions for investigative agencies – like the NTSB – which is why the PUC has offered other alternatives” to the NTSB such as inspecting, but not taking or copying, unredacted documents.

But doesn’t federal law trump state law? The NTSB believes so. A judge could ultimately decide the answer to that. The NTSB has issued a subpoena for the documents.

The PUC agrees the NTSB’s move is unprecedented but for a different reason.

“This is a unique situation where a federal agency is demanding that the PUC violate state law,” the commission’s statement said. “In the more than 16-year history of the Pennsylvania CSI Act, we have not encountered this situation with the NTSB or any other federal investigative agency.”

Spokesmen for both the NTSB and PUC declined to comment beyond the agencies’ published statements.