One thing that was left in Iran during the fall in 79, was all the Bell production facilities and tooling. They were building AH-1J Sea Cobra and UH-1N/212 and Bell 214s there. All that stuff was left behind. Iranian mechs had been working on these helos and other, along with jets and large Boeing/Lockheed planes, so none of this was new to them, but they did have to get production stuff translated over to Farsi. What parts they didn’t have, they manufactured. But they did start running out of parts.
Then, in the early 1980s, some real politik happened. The US needed to fund the anti-communist Contras group in El Salvador who were fighting the communist Sandianistas of Nicaragua required funding and arming. Congress had forbidden the Reagan administration of directly funding them. So, the plan to indirectly fund them, went into motion. The Iran/Contra plan saw the US in back channel communications with Iran, who was having a hell of a time in their war with Iraq, which started at the worst possible time for Iran…immediately post-revolution. Iran needed equipment. US needed the Contras funded. US agreed to send secondhand mil equipment to Iran, which is what they were operating anyway, in exchange for Iran putting the money for those items into an account funding the Contras. Iran received TOW missiles, early gen M16s and M60s, tons of ammo for same, 90mm and 106mm recoilless rifles, Redeye SAMs, Hawk SAMs, lots of parts for UH-1 and AH-1 helos, mostly models we didn’t fly ever or flew upgraded models of. Parts for F-4s sent through other countries and munitions like Mk series bombs with early PW-1 guidance kits, early EO AGM-65 missiles, lots of bench stock that we didn’t use much anymore. That’s a big part of how they have been able to sustain their 1980s military for so long. The helo that the President was riding on was likely well maintained, or perhaps if a Mx cause to this crash, had something fail or a maintainer failure like happens to any other aircraft. Or if pilot error, likely no different than what happened to pilots anywhere. It’s interesting and impressive what the Iranians have been able to maintain as frontline equipment, including doing depot-level rebuilds and Mx.