Solution : https://service.sap.com/sap/support/notes/73033 (SAP Service marketplace login required)
Summary : 
      
Key words : 
component quantity 1 piece + 10% component scrap, additional key words co01, reference field rc27x-flg_sel, reference field sy-datar, function module co_mk_resb_amount create, status short text 'mneu', function module co_it_dum_ass_upd, system status i0361, incorrect component quantity, import parameter new_calc
Related Notes : 
       
| 541861 | COHV: Reset availability data for assembly orders | 
| 306639 | Incor.reqmt qty rounding co-products/by-products | 
| 305596 | Size: BDMNG does not correspond to ERFMG in order | 
| 170088 | Var.-size itms:Var.-size itms no.incr.if rqmt qty 0 | 
| 158411 | CO01,02:Incor. qties f.dirctly manufactrd component | 
| 112062 | CO01/02:Incor. phantm qties when changing headr qty | 
| 110734 | CO01: Requirement quantity of a size not rounded | 
| 108300 | Incor.size quantities after change i. qty i. header | 
| 101007 | Wrong qantty t.be dscntnud for header qantty change | 
| 100901 | COR1,COR2: Chnge header qantity=>cmpnent quantities | 
| 94053 | Incor. component qty when converting planned order | 
| 89557 | Cost est with quantity struct: Rounding indicator 1 | 
| 80204 | Wrong component quantity in production order | 
| 79149 | Alternative UoM: Incorrect adjustment of comp. qties | 
| 78687 | Wrong component qty when converting planned orders | 
| 77187 | Computation of quantities for material components | 
| 63939 | Rounding error when changing phantom assembly | 
| 52784 | MF40: component quant. + MF43: secondary require. | 
| 43594 | CO01: wrong ord.fin.date (in-hou. prod. time = 0) |