PARIS — Mobile satellite services provider Iridium Communications on Oct. 29 said the inaugural launch of its second-generation constellation had slipped again and now will not occur before April.

The delay, from December, will automatically push the second launch — of 10 satellites on a SpaceX Falcon 9 rocket — back by four months, to August. Iridium’s insurers want the company to test the performance of the first two satellites, to launch on a Russian-Ukrainian Dnepr rocket, for several months before launching the rest of the constellation.

Iridium said it had concluded an agreement with its creditors on a revised insurance regime for the launches — one that will relieve Iridium of a near-term cash expenditure but add the risk of higher-priced insurance if one of the company’s early launches were to fail.

Under the latest schedule, the Dnepr launch of two Iridium Next satellites in April will be followed, in August, by the first of seven lridium launches on Hawthorne, California-based SpaceX’s Falcon 9 rocket from Vandenberg Air Force Base, California. Each Falcon 9 will carry 10 Iridium Next satellites.

McLean, Virginia-based Iridium is counting on SpaceX’s being able to conduct launches every two months or so, which would mean all seven would be completed by September 2017.

In a conference call with investors, Iridium Chief Executive Matthew J. Desch made no attempt to hide his exasperation at the latest delay, especially because it was caused by a component that had posed issues for prime contractor Thales Alenia Space previously.

The component, built by ViaSat Inc. of Carlsbad, California, is an extension of a Ka-band transmit/receive module. This hardware already had been associated with production delays on Iridium Next.

“Thales now appears to have found an issue during post-assembly testing of this same T/R module,” Desch said. The defect “could create performance problems in the Ka-band downlink to our Earth stations.”

Thales Alenia Space of France and Italy will now change the circuitry in the module and then reinstall it onto the first two satellites to launch on Dnepr.

“This is particularly frustrating in that it should have been caught and resolved much earlier in development,” Desch said. “In light of previous program delays, Thales Alenia knows — quite clearly — my disappointment.”

Thales Alenia Space issued a statement Oct. 29 saying the technical issues surrounding the transmit/receive module have been resolved. The company said it was accelerating the Iridium Next production rate to be ready for the follow-on launches after the inaugural flight and to assure that the full 72-satellite constellation is deployed by the end of 2017.

Desch said Iridium’s current satellites, all well past their expected retirement dates, remain healthy and that a recent assessment of their status given the new launch schedule has found no reason to doubt that a smooth transition will take place with no disturbance to Iridium’s subscribers.

“We monitor and measure network performance on a daily basis through more than 1,000 calls, testing signal strength, call routing, connectivity and duration,” Desch said during the conference call.

Under an amended agreement with its lenders, Iridium is no longer obliged to secure insurance for the full constellation before the first launch. Instead, it must assemble coverage for the first three launches — the Dnepr and the first two SpaceX Falcon 9 launches — at least three months before the Dnepr flight.

The insurance will cover the satellites’ launch plus their first year in orbit. If one of the first two Falcon 9 rockets fails, Iridium will use the nine spare satellites Thales Alenia Space is already building for a replacement flight, plus a 10th satellite that will be financed by the insurance claim along with a fresh launch.

No later than three months before the third SpaceX flight, Iridium must have purchased coverage for all five remaining launches.

A failure of one or two satellites on each of these launches will not be covered by insurance. But if a third satellite fails, insurers will pay a claim for all three — or more — plus a pro rata share of the launch costs.

Iridium Next has been budgeted at $3 billion, including a $2.3 billion contract with Thales Alenia Space for 81 satellites, of which $1.5 billion had been paid as of Sept. 30. The SpaceX launch contract is budgeted at $453.1 million for seven launches of 10 satellites each, of which $188 million had been paid as of Sept. 30, Iridium said in an Oct. 29 filing with the U.S. Securities and Exchange Commission.

Iridium has paid SpaceX an additional $3 million to reserve future launches and has secured an extremely low-priced reflight in the event of a Falcon 9 failure.

The Dnepr flight is costing Iridium $51.8 million — $34 million of which has already been paid. In June, Iridium replaced the expired option for two additional Dnepr flights with an option for up to six additional Dnepr launches. Launches will occur from Russia’s Yasny spaceport.