ftl_check: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/sbin/ftl_check - from package: mtd-utils

You may install the required package with command apt-get install {package}
Error in other languages:
ftl_check: bevel nie gevind nie
ftl_check: comandă negăsită
ftl_check: comando não encontrado
ftl_check: commande introuvable
ftl_check: command not found
ftl_check: käsku ei ole
ftl_check: không tìm thấy lệnh
ftl_check: komanda nerasta
ftl_check: Kommando nicht gefunden.
ftl_check: kommandot finns inte
ftl_check: komut yok
ftl_check: nie znaleziono polecenia
ftl_check: níor aimsíodh an t-ordú
ftl_check: no se encontró la orden
ftl_check: no s'ha trobat l'ordre
ftl_check: opdracht niet gevonden
ftl_check: parancs nem található
ftl_check: perintah tidak ditemukan
ftl_check: príkaz nenájdený
ftl_check: příkaz nenalezen
ftl_check: команда не найдена
ftl_check: командата не е открита
ftl_check: 命令找不到
ftl_check: コマンドが見つかりません