23.1001 Fuel jettisoning system (Amendment 23-51)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.30
Related Material
AC 23-8B, Flight Test Guide for Certification of Part 23 Airplanes
Paragraph 23.1001(a)
ADC Cross-reference: 5.30
What is the definition of maximum weight as used in § 23.1001(a)?
The maximum weight to be used in calculating the fuel jettison rate is the maximum takeoff weight of the airplane. This is supported by Amendment 23-7, which, for the most part, used the requirements of § 25.1001 as a new § 23.1001. At the time, § 25.1001 stated that the calculation was to use maximum takeoff weight.
Paragraph 23.1001(b)
ADC Cross-reference: 5.30(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1001(c)
ADC Cross-reference: 5.30(a)(1), 5.30(a)(2), 5.30(a)(3), 5.30(a)(4)
What methods are typically used to show compliance with § 23.1001(c)?
Colored fuel or a surface treatment that changes appearance upon contact with fuel or fuel vapor has been used to detect surface impingement. Combustible mixture detectors, scent, or visual inspections have been used to detect fuel or fuel vapor entering portions of the airplane.
Paragraph 23.1001(d)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
Paragraph 23.1001(e)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
Paragraph 23.1001(f)
ADC Cross-reference: 5.30(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1001(g)
ADC Cross-reference: 5.30(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1001(h)
ADC Cross-reference: 5.30(d)
No specific policy is available as of December 31, 2002.
OIL SYSTEM
23.1011 General (Amendment 23-43)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.31
Paragraph 23.1011(a)
ADC Cross-reference: None
This guidance may be used for Airship Certification as applicable.
Can the part 33 certification of oil system components be used to show compliance with § 23.1011?
Oil systems and components certified with the engine may or may not be suitable for use in a specific airplane installation, depending upon the test/analysis performed at the time.
Also, engines may be originally certified with the intention of being installed in different airplanes than where they are eventually used. Consequently, oil systems and components approved during engine type certification are only acceptable for use without further substantiation when they complied with standards that are equal or more stringent than those in this subpart.
Evaluate each pertinent item in the installation to assess the airplane requirements versus the requirements demonstrated during engine certification. Verify the latter with the engine manufacturer or the FAA office controlling the engine type design.
Paragraph 23.1011(b)
ADC Cross-reference: 5.31(a)
What are the requirements for continued safe operation of the engine(s)?
The engine requirements for oil quantities and temperatures are established by the engine manufacturer and may be found on the Type Certification Data Sheet or in the engine installation manual. The airplane installation must not cause the engine limits to be exceeded under normal operations.
Paragraph 23.1011(c)
ADC Cross-reference: 5.31(b)
How much oil must the system contain?
Paragraph 23.1011(c) requires that, “The usable oil tank capacity may not be less than the product of the endurance of the airplane under critical operating conditions and the maximum oil consumption of the engine under the same conditions, plus a suitable margin to ensure adequate circulation and cooling.” In other words, there needs to be enough oil (usable supply) to allow the engine to consume the usable fuel. This should be substantiated by a quantitative analysis.
In addition, a suitable oil quantity margin for system circulation is necessary for all engine installations. The oil system should be capable of maintaining the engine within its operating limitations (i.e., oil temperature with the minimum oil quantity provided for circulation). Cooling tests do not need to be performed with a low usable oil supply provided the oil is properly cooled at all oil levels.
What are the definitions of some of the terms used to determine the required oil quantity?
Usable Oil
Usable oil is defined as the quantity of oil in the oil tank (or sump in the case of wet sump engines) in excess of the minimum quantity of oil required to keep the oil pump inlet feed covered under the most adverse operating condition.
Without any other data, the most severe of the following two conditions may be used as the most adverse operating condition (in both cases, with the airplane at a zerodegree roll angle):
1. The nose-up pitch angle required for the sea level best rate-of-climb speed with maximum continuous power, or
2. The nose-down pitch angle required for the 1.3 V SO power-off landing configuration.
For most wet sump engines, the usable oil quantity for various pitch angles is listed on the appropriate engine Type Certificate Data Sheet (TCDS). This quantity may be used instead of a determination of usable oil as described above. If the usable quantity is not listed, it may be determined by contacting the engine manufacturer or conducting a usable oil test with the critical operating conditions.
Usable Fuel
The usable quantity of fuel is established under § 23.959.
Specific Oil Consumption (SOC)
The SOC is the maximum oil consumption rates established by the engine’s manufacturer, expressed in pounds per brake horsepower per hour (lb./bhp/hr.). If such a maximum oil consumption rate is not available, use 0.012 lb./bhp/hr. for reciprocating engines. There is no similar “default” maximum oil consumption rate for turbine engines.
You can also establish an oil consumption rate by the following:
1. Statistical analysis of actual in-service oil consumption rates. The analysis should include observed data on the actual oil consumption from statistically valid sample engines of the same model. These data should be obtained from high time engines or those with high oil consumption just before removal for overhaul.
2. Testing according to an FAA-approved test plan. Testing for a lower oil consumption rate should include a positive demonstration that a lower oil consumption rate will not jeopardize the airworthiness of the engine.
Specific Fuel Consumption (SFC)
SFC is the fuel consumption established for the engine based on available engine power expressed in pounds per brake horsepower per hour.
What are the acceptable means of compliance for § 23.1011(c)?
Single-engine Installations
Determine the minimum allowable usable oil capacity from the airplane’s endurance (~total fuel capacity divided by the minimum SFC) and the maximum allowable oil consumption rate. For either wet or dry sump engines, this is expressed mathematically as follows:
[Minimum Usable Oil Capacity (lbs.)] =
[Maximum Usable Fuel Capacity (lbs.)] x [Maximum SOC (lb./bhp/hr.)] [Minimum Obtainable SFC (lb./bhp/hr.)]
A usable oil capacity greater than or equal to the calculated number above is acceptable.
Multiengine Installations
Calculate the minimum usable oil capacity for a multiengine aircraft as above, except modify as follows:
Account for the additional usable fuel if the airplane has a fuel cross-feed system or common fuel tank in the event of an engine shutdown. Allocate 50 percent of the maximum usable fuel capacity attributable to the shutdown engine as available to the other engine(s). For example, for a twin-engine airplane with 1,000 pounds of maximum usable fuel, 500 pounds of which is attributed to the shutdown engine, add 50 percent of that (250 pounds) to the available fuel.
In addition, adjust the fuel consumption of the remaining engine(s) to reflect any power or mixture setting changes made to complete the flight safely.
Paragraph 23.1011(d)
ADC Cross-reference: 5.31(c)
What oil quantity should be used in finding compliance with § 23.1011(d)?
A conventional system (no transfer system provided) should only consider the usable oil tank or sump capacity to determine the usable oil supply. Do not consider the quantity of oil in the engine oil lines, in the oil radiator, oil filter, propeller feathering reserve, etc. If the airplane manufacturer elects to operate the engine with less than total oil capacity, the lower oil level should be used in the analysis.
Paragraph 23.1011(e)
ADC Cross-reference: 5.31(d)
Is it possible to consider oil in transfer lines as part of the usable oil?
When an oil reserve system is installed, additional oil may be available. The system is often configured so the transfer pump can pump oil into the main engine oil tank(s) from the transfer lines. In this case, include the quantity of oil that would be pumped to the main engine oil tank(s) to determine the usable oil supply.
23.1013 Oil tanks (Amendment 23-51)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.32
Paragraph 23.1013(a)
ADC Cross-reference: 5.32(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1013(b)
ADC Cross-reference: 5.32(b)
What is the difference between the expansion space requirements in § 33.71(c) and § 23.1013(b)?
The requirements of § 33.71(c) and § 23.1013(b) are similar, and both the engine manufacturer and the installer must show compliance to the oil tank expansion space requirement. When showing compliance with § 23.1013(b), data from the certification of the engine to § 33.71(c) may be used. Compliance with the installation requirements should account for any installation affects including wing dihedral, installed engine droop, and yaw angles. This could require ground test of both a left and right wing engine if adequate data is not available from the part 33 compliance demonstration.
Sometimes, the oil quantity in the tank may change with changing engine operating conditions such as engine rotation. This condition can result in overfilling the engine oil tank resulting in less than the required expansion space if the tank is serviced soon after engine shutdown. If conditions like this exist, they can be handled by oil system servicing limitations in the appropriate manuals with placards near the fill port.
Paragraph 23.1013(c)
ADC Cross-reference: 5.32(c)
No specific policy is available as of December 31, 2002.
Paragraph 23.1013(d)
ADC Cross-reference: 5.32(d)
No specific policy is available as of December 31, 2002.
Paragraph 23.1013(e)
ADC Cross-reference: 5.32(e)
No specific policy is available as of December 31, 2002.
Related Material
AC 20-135, Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
AC 23-2, Flammability Tests
NOTE. If there are differences between AC 20-135 and AC 23-2 (see below for AC title), the applicant may choose the advisory circular that is either most applicable or most advantageous, or both.
Paragraph 23.1013(f)
ADC Cross-reference: 5.32(f)
No specific policy is available as of December 31, 2002.
Paragraph 23.1013(g)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.
23.1015 Oil tank tests (Amendment 23-15)
CAR 3 Cross-reference: None
ADC Cross-reference: 5.33
Paragraph 23.1015(a)
ADC Cross-reference: 5.33(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1015(b)
ADC Cross-reference: 5.33(b)
What test setup and procedures are typically used for the slosh test in § 23.1015(b)?
Refer to § 23.965(b) for a description of the test setup and procedure.
Related Material
TSO-C80, Flexible Fuel and Oil Cell Material
Paragraph 23.1015(c)
ADC Cross-reference: 5.33(c)
No specific policy is available as of December 31, 2002.
23.1017 Oil lines and fittings (Amendment 23-14)
CAR 3 Cross-reference: 3.570, 3.575
ADC Cross-reference: 5.34
Paragraph 23.1017(a)
ADC Cross-reference: 5.34(a)
No specific policy is available as of December 31, 2002.
Paragraph 23.1017(b)
ADC Cross-reference: 5.34(b)
No specific policy is available as of December 31, 2002.
23.1019 Oil strainer or filter (Amendment 23-43)
CAR 3 Cross-reference: 3.573
ADC Cross-reference: 5.35
Paragraph 23.1019(a)
ADC Cross-reference: 5.35(a)
Can the engine oil pressure indicator be used to comply with § 23.1019(a)(3)?
The engine oil pressure indication may be used as a method of detecting oil filter/strainer contamination provided the applicant demonstrates a procedure that does the following:
1. Identifies the oil strainer/filter contamination, and
2. Isolates the contamination as the sole cause of an indicated oil pressure change.
The procedure used to comply with § 23.1019(a)(3) should be documented in the Airplane Flight Manual.
Can a red warning light be use to comply with § 23.1019(a)(5)?
A red warning light is one means of complying with § 23.1019(a)(5).
Paragraph 23.1019(b)
ADC Cross-reference: 5.35(b)
No specific policy is available as of December 31, 2002.
23.1021 Oil system drains (Amendment 23-43)
CAR 3 Cross-reference: 3.574
ADC Cross-reference: 5.36, 5.36(a)
Paragraph 23.1021(a)
ADC Cross-reference: 5.36
No specific policy is available as of December 31, 2002.
Paragraph 23.1021(b)
ADC Cross-reference: 5.36(b)
No specific policy is available as of December 31, 2002.
Paragraph 23.1021(c)
ADC Cross-reference: None
No specific policy is available as of December 31, 2002.