REDU format ruling
Commander Covington
Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)You can send 1 face-up "Machina Soldier", "Machina Sniper", and "Machina Defender" you control to the GY; Special Summon 1 "Machina Force" from your hand or Deck.
Rulings
This effect doesn't target.
Sending "Machina Soldier", "Machina Sniper", and "Machina Defender" to the GY is a cost.
You cannot send any of the listed 'Machina' cards to the GY if they are being treated as Equip Cards.
If you do not have a "Machina Force" in your hand or Deck, you cannot activate the effect of "Commander Covington". If you no longer have one when the effect resolves, your opponent can ask to verify.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.