Feem ntau, thaum cov chaw tsim khoom hauv lub raj mis tsim cov iav fwj, qee qhov tsis tshwj xeeb yuav ua rau muaj teeb meem nrog kev ua kom zoo ntawm lub khob cawv txiv hmab. Tsuas yog los ntawm kev them nyiaj ntau dua thaum lub sijhawm tsim khoom tuaj yeem zam cov teeb meem no rau qee yam. Cov yam tseem ceeb uas cuam tshuam rau qhov ua tiav ntawm lub khob cawv cawv yog qhov yooj yim rau txhua tus kom tsis txhob muaj qhov tshwm sim no thaum tsim cov iav fwj.
Qhov ua rau npuas. Thaum tsim cov iav fwj, yog tias koj pom tias muaj ntau cov npuas me me ntawm lub khob cawv txiv hmab, qhov laj thawj ntawm qhov tshwm sim no yog tias cov iav gob kua tsis huv los yog qhov kub ntawm lub iav gob tsis zoo li qub. Nws yog qhov yuav tsum tau ua kom peb ua tib zoo saib xyuas kom huv si thiab qhov kub thiab txias ntawm cov iav gob thaum lub sijhawm tsim khoom kom tsis txhob muaj qhov tshwm sim no.
Ua rau qhov chaw txias. Tom qab lub raj mis tsim tawm, yog tias muaj qhov chaw ntawm lub khob iav, peb hu nws qhov chaw txias. Feem ntau, qhov xwm txheej no yog tshwm sim los ntawm qhov pib pwm ntawm lub khob iav los ntawm kev hloov tsis raug ntawm tuyere thaum lub sij hawm tsim lub khob iav. Thiab qhov kub molding tsis sib koom ua ke. Thaum tsim cov iav cawv fwj, peb yuav tsum tau them sai sai rau kev kho cov tuyere, kom qhov xwm txheej no tuaj yeem zam tau.