Eastern Air Lines flight 836, a Boeing 727-225, with 152 passengers and 7 crewmembers aboard, took off from Miami International Airport, FL (MIA). The flightcrew stated that the climbout was normal until the flight reached approximately 10,900 feet. At that point a loud bang was heard, followed by illumination of the red DOORS and red RIGHT GEAR warning lights above the landing gear lever. In accordance with prescribed procedures, the first officer moved the landing gear lever from the OFF to the UP position. Following the first officer’s actions, the second officer reported loss of fluid and pressure in the A and B hydraulic systems. The primary flight controls reverted to manual operation, and the climb was terminated. The second officer attempted to view the right main landing gear and wheel well through an inspection port located in the cabin floor. However, because the wheel well lights had been damaged and did not illuminate, he could not see into the wheel well. He then used a flashlight but found that the wheel well side of the inspection port was coated with hydraulic fluid which obscured illumination and vision through the port. The airplane then was flown over runway 27R at the Miami Airport. Eastern observers on the ground reported that the right main landing gear doors were open but that the gear position could not be seen. Eastern flight 511, which was preparing for takeoff, reported to the tower and flight 836 that the right main landing gear doors were not fully open. The captain decided to lower all landing gear using the emergency manual extension procedures. The second officer first extended the left main landing gear and the green LEFT GEAR light illuminated. He attempted then to extend the right main landing gear and noted that the manual extension system appeared to operate normally. However, the red RIGHT GEAR warning light remained illuminated. The nose landing gear was next extended and the green NOSE GEAR light illuminated. The captain then retarded one of the throttles and the landing gear warning horn activated, indicating that one or more landing gears were not down and locked. When a second fly-by over runway 27R was made, Eastern observers on the ground reported that the right main landing gear doors were open but the right gear was not extended. The second officer then made additional attempts to manually extend the right gear, and the captain maneuvered the airplane in an attempt to dislodge it. Both actions were unsuccessful. The captain electrically extended the trailing edge flaps and, using the standby hydraulic system, hydraulically extended the leading edge flaps and slats with the alternate flap extension system. He landed the airplane on the extreme left side of runway 9R and decelerated the airplane using reverse thrust and pneumatic brakes. He attempted to keep the right wing off the runway as long as possible. When the right wing contacted the runway, the airplane veered to the right and departed the runway. The left main landing gear and the lower portion of the nose landing gear separated from the airplane. The nose gear punctured the right wing fuel tank, and fuel spilled out. The airplane stopped about 2,500 feet from the departure end and about 100 feet to the right (south) of runway 9R. There was no fire; the airplane was substantially damaged. The Safety Board’s investigation determined that the No. 3 tire failed explosively in flight while retracted in its wheel well, due to massive ply separations around its crown, severely damaging the hydraulic lines for the A and B hydraulic systems running through the right wheel well. The origin of the ply separations was located along the chafer strip/toe bead area which had extensive previous damage from two sources–abrasion and excessive heat. Damage from either source would have allowed high-pressure nitrogen (approximately 175 psig) to enter the ply system under dynamic conditions, causing ply separation. PROBABLE CAUSE: landing gear,tire .. previous damage hydraulic system .. no pressure maintenance,installation .. improper .. other maintenance personnel door,landing gear .. movement restricted landing gear,tire .. overtemperature landing gear,tire .. exploded hydraulic system .. disabled emergency procedure .. Poor