Revised Special Airworthiness Information Bulletin Focuses On
Engine Cooling
The FAA has issued a revised SAIB for aircraft with
Bombardier-Rotax (Rotax) 912 A, 912 F, 912 S, and 914 F series
reciprocating engines for a possible problem with the liquid
cooling system. These engines are installed on, but not limited to,
Aeromot-Industria Mecanicao Metalurgica AMT-200, AMT-200S, and
AMT-300; Aquila Technische Entwicklungen GmbH AT01; Diamond
Aircraft Industries (Austria and Canada) DA20-A1, HK36 R, HK36 TC,
HK36 TS, HK36 TTC, HK36 TTC-ECO, and HK36 TTS; Iniziative
Industriali Italiane 650 TC, 650 TCN, 650 TCS, and 650 TCNS; and
Stemme GmbH S10-VT aircraft. They may also be installed on
amateur-built and light-sport aircraft.
The European Aviation Safety Agency (EASA) has advised the FAA
of possible loss of coolant and engine overheating on Rotax 912 and
914 series engines. Based on these findings, EASA published AD
2007-0155, dated May 29, 2007, that requires use of a waterless
type coolant if the engine coolant exit temperature will exceed
120° centigrade (C). Use of waterless coolant may not apply to
all Rotax 912 and 914 series engines because coolant exit
temperatures are affected by the aircraft installation and
operating conditions. The maximum cylinder head temperature
limits approved for these engines remain the same.
If a conventional ethylene-glycol/water coolant is used, and
engine coolant exit temperatures exceed 120° C, loss of
coolant, engine overheating, knocking, and engine damage can occur,
which could result in an in-flight shutdown. The coolant exit
temperature should be monitored to prevent engine overheating when
using conventional coolant. Engine overheating can be prevented by
monitoring cylinder head temperature if an appropriate correlation
is established between coolant exit temperature and cylinder head
temperature.
Rotax 912S
The FAA recommends following the coolant usage information
provided in Rotax service bulletins SB-912-043 Revision 2, dated
November 10, 2006, and in SB-914-029 Revision 2, dated November 10,
2006, and the applicable Rotax 912 and 914 installation manuals and
operator’s manuals. They further recommend that pilots and
owners comply with the coolant usage information and cooling system
temperature limits defined by the manufacturer of your aircraft
because of installation effects on engine cylinder head and coolant
exit temperatures.