When the National Transportation Safety Board issues its preliminary report — possibly as early as next week — on the probable cause of the deadly explosion and fire at the Flower Branch Apartments, living conditions in the Silver Spring complex are unlikely to play a major role.

But they were a recurring theme at a three-hour Montgomery County Council hearing Tuesday on the natural gas-fed inferno that killed seven, injured 39 and left 63 families homeless. The August 10 disaster on Arliss Street has triggered a debate over how often the county’s 67,000 apartments should be inspected — especially those in buildings with histories of housing code violations.

At the hearing, several council members pressed housing director, Clarence Snuggs, whose department handles code enforcement, for a more robust inspection system.

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Apartment buildings are inspected triennially. Officials have the option of sampling anywhere from 10 to 100 percent of the units in a building, depending on its age and overall condition.

In three rounds of inspection since 2007, every unit at Flower Branch was examined. Records show repeated findings of mice, roaches, bed bugs, mold from water damage and other problems.

The most recent inspections, in 2013, identified more than 400 violations in the 362-apartment community. In 2010 inspectors spotted 698 violations. According to housing department data, all of the conditions were eventually corrected. Landlords who do not address violations can be taken to court and fined.

Council member Tom Hucker (D-Silver Spring), whose district includes the predominantly Latino Long Branch neighborhood where the apartments are located, told Snuggs that more frequent inspections seemed essential.

“Don’t you look at this and think this is an apartment building that’s aging and has persistent violations and should be inspected every year or two years?” he asked.

Snuggs pointed out that not all of the violations found at the complex were life-threatening. But he said his department is “looking at our strategy on how to focus on issues like this.”

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Kay Management, owner of Flower Branch, moved some displaced tenants into nearby Northwest Park, another building the company owns. Recent inspection records found about 2,200 violations in the 800-unit complex — many of the same kind that were found in Flower Branch.

“So the traumatized individuals from Flower Branch, some of them were relocated there?” Hucker asked.

Snuggs said it was “a leap” to assume that Flower Branch victims were moved into apartments that had code issues.

Kay president Clark Melillo has disputed claims of poor conditions, describing the county citations as “terribly small” and quickly corrected.

Records show relatively few tenant complaints in the years between triennial inspections. Advocates say this is a sign that residents, primarily the immigrant working poor, are reluctant to reach out for assistance because of possible reprisals from landlords.

A bill to overhaul landlord-tenant relations, sponsored by council member Marc Elrich (D-At Large), originally included a provision requiring annual inspection of all apartments, a proposal rejected by Snuggs as costly and unnecessary.

Elrich now advocates “an inspection surge,” in which officials would eyeball all apartments over a period of one to two years before deciding which buildings warrant annual visits.

“We cannot make a rational decision right now about who goes on what schedule,” Elrich said. His bill would also allow tenants to make repairs and deduct the cost from their rent if landlords are unresponsive. The measure is currently before the council’s planning, housing and economic development committee.

Snuggs said after the hearing that he was still working on his own proposal for the committee. He called the situation “very much evolving and dynamic.”

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The NTSB, usually in the public eye for investigations of air and railway crashes, also probes the origins of explosions involving pipelines that are under federal regulation. In this case, that means service lines operated by Washington Gas.

Paul Sledzik, NTSB deputy director for safety recommendations and communications, told the council Tuesday that a preliminary report would probably be available within the next week or so.

While the inquiry is still ongoing, Sledzik said, tests showed no evidence of leaks in the Washington Gas service line that runs underground and extends about a foot inside the building. The remainder of the line inside the apartment building, up to and including meters and regulators, was damaged by the explosion and could not be tested. Pieces of the regulators are under laboratory study, Sledzik said.

Lines that run beyond the meters into individual apartments are the responsibility of building management. All new installation of plumbing from the meter to inside the apartments is supposed to be inspected by WSSC.