TM10-3930-660-34 16-12.  BOOM ASSEMBLY - REPLACE (Cont’d) WARNING Before  performing  step  3a,  make  sure  hoses  (11)  at  front  of boom   assembly   (8)   are   closed   securely   using   metal   plugs. Hydraulic oil under pressure can spray from hoses (11) causing bodily injury if hoses are not closed securely. a. Start engine and raise boom assembly (8) as necessary to access hoses (9).Stop engine. WARNING Disconnect hoses (9) carefully during step lb. Hydraulic oil may be under pressure. b. Tag  and  disconnect  three  hoses  (9)  from  lines  (10)  at underside  of  boom  assembly  (8).Plug  three  hoses  (9) with metal caps. 4. DISCONNECT  ROD  END  OF  BOOM  HOIST  CYLINDERS (12) FROM BOOM ASSEMBLY (8). a. Start  engine.    Lower  boom  assembly  (8)  until  cylinder pivot pins (13) are just above cab.  Stop engine. b. Support boom assembly (8) with hoist and slings or other suitable    lifting    device    positioned    at    front    of    boom assembly (8). c. Place  wood   block   across   vehicle   deck   behind   cab   to support  boom   hoist   cylinders   (12)   when   cylinders   are lowered. 16-50