Airworthiness Advisory Circulars - Part 6-46 - General advice
Part 6 - General advice
Leaking Fuel Line Hoses
Aeroquip, a United States hose manufacturer, has issued Service Bulletin AA135 covering leakage of the 601 medium pressure hose when used to carry Aviation Gasoline. At this time the condition has been reported in aircraft operating in the US and Australia. To ensure that all Certificate of Registration holders, Owner and Operators of piston powered aircraft in Australia have been advised, the SB is being re-printed in its entirety with the kind permission of Aeroquip Corporation, Aerospace Group, Hose Product Division, 300 South East Avenue, Jackson. Michican 49203 USA.
Note: It should be noted, however, that further to the Article below, Aeroquip have advised that where the subject fuel hose is used in a firezone, the recommended Teflon hose must be fire sleeved. The AE400 series with integral silicone firesleeve or AE102 or AE271 silicone coated fibreglass firesleeves are suitable for such applications.
"TO OWNERS/OPERATORS OF ALL GENERAL AVIATION AIRCRAFT USING AVIATION GASOLINES (E.G., INCLUDING, BUT NOT LIMITED TO, 100 OCTANE LOW LEAD, HIGH OCTANE AUTOMOTIVE UNLEADED, ETC., HEREINAFTER REFERRED TO AS "AVIATION GASOLINE").
Aeroquip Corporation's Aerospace Group has recorded several failures of its 601-type hose over the past 12-month period. The subject hose meets all required specifications, however, based on data accumulated to date, it appears that the use of this hose in fuel systems which carry AVIATION GASOLINE is adversely affecting the life expectancy and performance which Aeroquip has historically experienced with this type of hose. Aeroquip has seen degradation of the elastomeric inner tube which has resulted in the tube cracking, which , in turn, has caused leaking of the 601 hose in these limited types of applications. Based on the data which Aeroquip has accumulated to date, it appears that this phenomenon is occuring after approximately two (2) years installation time (independent of actual service hours on the subject hose). To the extent your aircraft may be affected by this phenomenon, Aeroquip recommends that you inspect your aircraft to determine: (a) if your aircraft has 601-type hose fuel lines: and (b) the age and conditions of said hoses. Aeroquip strongly recommends that any 601 hoses, which is approaching, or has more than two (2) years in an aviation gasoline application, be replaced in accordance with the recommended action outlined in this Service Bulletin.
Note: This Service bulletin does not apply to applications using Jet A, JP4, JP5 or JP8 grades of fuel commonly used for turbine/jet engines. It also does not apply to other fluids such as lubricating oils, REF. MIL-L-7808 or MIL-L-23699.
HOW TO IDENTIFY 601 HOSE ASSEMBLIES AND AGE:
|I. Aeroquip 601 hoses have a red socket|
|II. Locate metal identification tag (see example)|
|. 601 hoses typically begin with part number 601xxx|
|. Hoses that begin with AE701xxxx are not covered by this Service Bulletin. Most Cessna twins use AE701 type hoses.|
|I. Review maintenance log books to determine if hose has been installed for two years.|
|II. If maintenance records are not available, refer to the assembly date quarter/year (see example). Any hose with an assembly date of A4Q90 or before should be considered to have been installed for two years or more.|
|III. If no maintenance records or identification tag is available, the hose should be removed and replaced.|
|Example:||Aeroquip-xxx||Hose Assy Location|
|601000-4-0300||Example Hose Part Including Length|
|Customer Part Number||Bxxxxx-x-xxx|
|Example: Assembly Date (Quarter/Year)||A2Q90||2Q88||Example: Cure Date (Quarter Year)|
|Example: Proof Test Date (Month/Year)||PT5-90||xxxxx||FSCM No.|
|Hose Material||Rubber||xxxx psi||Operating Pressure|
As you know, all rubber hose, regardless of the nature of the application, experience degradation over time. However, the current phenomenon which Aeroquip is observing with its 601 hose appears to be caused and accelerated by the expanding use of Low-lead AVIATION GASOLINE in general aviation aircraft. Current aviation trends indicates that low-lead and even no-lead, fuels will be used in ever-expanding and broader applications in the future. For these reasons, Aeroquip strongly recommends replacement of the subject 601 hose with Teflon* hose assemblies. Years of research and service experience in the aviation industry indicates that superior performance and longer service life can be achieved through the use of Teflon hose.
* Teflon is a Registered trademark of Dupont.
If you choose to replace your current 601 hose assemblies with rubber hose, Aeroquip strongly recommends regular, periodic inspections and replacement of said hoses after approximately two years time. Although Teflon hose assemblies should also be subjected to regular periodic inspection, Teflon is normally unaffected by many of the operating variables which contribute to rubber hose degradation, and will give you superior performance and longer service life. Teflon hose alternatives are fully approved to FAA TSO C53 and TSO C75.
Aeroquip has established a comprehensive substitution programme under which the owner/operators may obtain Teflon hoses at a price which is approximately 10 to 20 percent lower than its 601 equivalent. (Price difference will vary according to configuration). For more detailed information regarding this programme, please contact one of the distributors listed and provide the distributor with the following Information:
Aircraft Registration Number:
Hose Assembly Part Number or Description:
Number of Hours Service
PARTICIPATING DISTRIBUTOR IN AUSTRALIA
Hawker Pacific Pty Ltd
4-8 Harley Crescent
CONDELL PARK NSW 2000
Phone :61 2 708 8555
Contact :Graham Rock
Fax :61 2 708 1480"