"Stinger and SA-7 missles are dropping our birds from the sky."
Or Russian-made SA-14 & SA-18 or Chicom copies of such. I'm sure both the Russian and Chicom arms makers have made sure their latest MANPADs, ATGWs, and tandem-warhead RPGs (such as the RPG-29) are making it to the Iraqi and Lebanese battlefields to see their effectiveness against Western combat systems.
There is still the possibility of mechanical failure, considering the age of the Sea Knight that was lost, but the reports by other pilots that witnessed it go down is more consistant with a SAM or RPG hit.