A training exercise for Maryland State Police involves practice in reaching the ground from an airborne helicopter. (Maryland State Police Aviation Command)

Maryland State Police took their medical helicopters out of service over the past three days to examine tail rotor blades after two recent inspections revealed cracked paint, officials said.

About half of the fleet of 10 was expected to still be out of service through Thursday morning, but police officials said they have been using medevacs from other police agencies to respond to emergency calls.

All but two areas — on the western and eastern edges of the state — are expected to have their Maryland police helicopters by the end of Thursday, state police spokesman Greg Shipley said.

“We have maintained medevac service throughout this period,” Shipley said. Helicopters from Delaware State Police and U.S. Park Police covered calls, he said.

Maryland uses AgustaWestland AW139 aircraft as its medical helicopters. Each aircraft’s tail rotor has four blades.

As of Wednesday afternoon, Shipley said, 36 blades from nine helicopters had been inspected.

Two dozen blades were deemed fine, because whatever paint cracks were found were addressed by new paint. The 12 other blades were sent to the manufacturer for further testing, although it is unclear if there is anything wrong beyond the paint cracks, Shipley said.

The 10th helicopter already was in Philadelphia at the manufacturer for routine maintenance when the issues arose, Shipley said.

New blades sent by the manufacturer Wednesday will replace the 12. After Maryland workers install them and test the helicopters, the remainder of the fleet will be put back into service.

“We are doing all of this out of an abundance of caution,” Shipley said.

NBC4 in Washington first reported the issues.

The problems surfaced on Jan. 9 during a regular inspection, when a maintenance worker noticed cracked paint on a tail rotor blade. The paint was sanded off and the blade itself was in good shape, Shipley said. The blade was repainted, and the helicopter went back in service.

On Sunday, during inspection of a different helicopter, cracked paint was found on a tail rotor blade. That was when state officials decided to immediately inspect all of the tail rotor blades, Shipley said.

The state fleet of medical helicopters has been widely debated since 2008, when one of the helicopters crashed, killing four of the five people on board, including a teenage patient and the crew. The state reduced its helicopter fleet from 12 to 10.

The state also replaced its aircraft, selecting the AgustaWestland AW139s.

Maryland Del. Jay Jalisi (D-Baltimore County), who sits on legislative panels with oversight over the helicopters, called Wednesday for the state police to release detailed inspection reports to shed light on the state’s helicopter maintenance and spending.

Having problems with most of the fleet “means the system is not working as it’s supposed to be working,” Jalisi said. “We shouldn’t have to ground any helicopters.”

Maryland State Police divide the state into seven coverage areas to deploy the helicopters. Until all of them are back in service, Shipley said, helicopters from other parts of the state or other agencies can be used.