Battle on the Principia

"You got about ninety seconds before the gravity field dissipates. After that, real gravity is gonna take over, and the ship's gonna fall out of the sky."

- Deke Shaw

The Battle on the Principia was a confrontation between S.H.I.E.L.D. agents who were searching Gravitonium on the flying Principia, and Sleeper Mechs left by HYDRA to guard the ship.

Background
"We're looking for a needle in a haystack." "Or a flying boat."

- Melinda May and Daisy Johnson

In the aftermath of the HYDRA Uprising, a cargo of Gravitonium was taken aboard the ship Principia owned by Cybertek. However, the ship was caught in a violent storm, which activated the Gravitonium's properties, causing the ship to be taken high up in altitude, killing the crew. Later, HYDRA leader General Hale found the ship and reclaimed most of the Gravitonium bulk as part of the Project Destroyer of Worlds she wanted to reinitiate. Hale was forced to leave the small quantity of Gravitonium responsible for keeping the ship in the air out of fear it could cause heavy damage. Coincidentally, S.H.I.E.L.D. also looked for Gravitonium in order to permanently seal the Fear Dimension which had opened in their base, the Lighthouse. With the assistance of Tony Caine and Joseph Getty, S.H.I.E.L.D. learned about the Principia. At first, they looked for it in the abyss, but Deke Shaw then had an epiphany and advised them to look in the sky, which enabled S.H.I.E.L.D. to successfully found the flying boat.

Battle
"On a mission with the two things I fear most: drowning and heights. Oh, make that three things." "What are those things?" "One of Hale's flying monkeys."

- Alphonso Mackenzie, Daisy Johnson and Phil Coulson

Using the Zephyr One's Containment Module and equipped with oxygen supplies, a S.H.I.E.L.D. team comprised of Phil Coulson, Daisy Johnson and Alphonso Mackenzie infiltrated into the Principia in search for the Gravitonium. They explored the ship's first deck without finding anything and went further into the ship. They found the crew of the Principia, who had been asphyxiated due to the altitude. Unbeknownst to the S.H.I.E.L.D. agents, however, several Sleeper Mechs hidden among the crew were activated.

The S.H.I.E.L.D. team then proceeded to the engine rooms, where they found the empty box of Gravitonium. However, Deke Shaw insisted that since the ship was still flying in the air, there had to be some Gravitonium somewhere. Indeed, Mackenzie soon located a ball of overcharged Gravitonium, which kept the boat in the sky. Thanks to Shaw's advice, Mackenzie was able to put this small quantity of Gravitonium in a plastic box, leaving the agents with about ninety seconds before the ship fell back into the sea. As the S.H.I.E.L.D. agents made their exit, they encountered the reactivated Sleeper Mechs. Recognizing them as the same androids they had faced during the Infiltration into St. Louis Aerospace Facility, the S.H.I.E.L.D. agents began fighting the androids to leave the ship before it fell. Despite their struggle, Coulson and Johnson managed to destroy several Sleeper Mechs and urged Mackenzie to follow them. However, Mackenzie decided to remain behind as he wanted to bring back a damaged android to the Lighthouse to salvage its arms for Yo-Yo Rodriguez.

The operation ended up a success. Mackenzie managed to defeat several androids on his own thanks to his Shotgun-Axe and dragged one of them to the Containment Module, where Johnson and Coulson awaited him. Mere seconds before the ship fell back into the ocean, the Containment Module took off and rejoined the Zephyr One.

Aftermath
"I just hope there's enough Gravitonium for them to work with. And I think it's safe to say General Hale has the rest." "I'm starting to think she's more than just an overzealous general."

- Phil Coulson and Melinda May

Despite having secured the Gravitonium, S.H.I.E.L.D. struggled to find a way to compress it enough to create an upgraded Gravity Containment Device and seal the Fear Dimension for good. It finally took a major psychic split of Leo Fitz, releasing his dark personality of the Framework, to solve the problem by forcefully removing Daisy Johnson's Inhuman Control Device and using her powers to compress the Gravitonium.

Having figured out Hale's involvement regarding the Sleeper Mechs they had faced during the battle, S.H.I.E.L.D. became even more suspicious towards her, still unaware that she actually was a leader of HYDRA. S.H.I.E.L.D. decided to capture Hale, although in the end it was Phil Coulson himself who ended up in Hale's custody.

Using the deactivated Sleeper Mech Alphonso Mackenzie brought back to the Lighthouse, Jemma Simmons implanted robotic arms on Yo-Yo Rodriguez in replacement for those she had lost during the Infiltration into St. Louis Aerospace Facility.