Crosswind compensation for outdoor testing of turbofan aircraft engine

1 . A method of crosswind compensation for an outdoor power assurance check test of a turbofan aircraft engine of an aircraft, comprising:

preparing data for engine under test by:

generating first tables representing average new engine (ANE) installed performance by running an estimated engine performance program (EEPP) to get expected values of a rotational speed of a high-speed spool (N2), an indicated turbine temperature (ITT), and combustor pressure (PB) with no deterioration and no crosswind effects;

generating second tables of sensitivities of N2, ITT, and PB to high-pressure compressor (HPC) deterioration, high-pressure turbine (HPT) deterioration, and fan work scaling by running the EEPP;

storing the first and second tables in a non-transitory storage accessible by an aircraft computer;

receiving the turbofan aircraft engine observed parameters of N2, ITT, and PB at an N1R1A at the aircraft computer by operating the aircraft computer to perform the power assurance check test of the turbofan aircraft engine by:

activating a brake of the aircraft;

closing the turbofan aircraft engine bleed system, hydraulic, and electric loads;

bringing the turbofan aircraft engine to Take-off power;

recording ambient parameters and the engine observed parameters once the turbofan aircraft engine is stabilized; and

bringing the turbofan aircraft engine back to idle;

calculating a difference between the engine observed parameters of N2, ITT, and PB at the N1R1A and corresponding ANE values of from the first tables as first deltas ΔN2, ΔITT, and ΔPB;

using the sensitivities from the second tables and the first deltas ΔN2, ΔITT, and ΔPB, solving a 3×3 system of equations to get a fan work scaling, an HPC efficiency debit, and an HPT efficiency debit;

calculating second deltas ΔN2, ΔITT, and ΔPB to ΔNE performance without inlet bulk swirl effect using the sensitivities from the second tables and a calculated HPC deterioration and HPT deterioration, without fan work scaling; and

calculating engine field margins for N2 and ITT by subtracting the second deltas ΔN2 and ΔITT from ΔNE field margins as an output for the outdoor power assurance check test.

2 . The method of claim 1 , wherein generating the first tables includes running the EEPP to a plurality of possible combinations of altitude, Mach number, temperature, humidity, and fan corrected speed N1R1A to get the expected values of N2, ITT, and PB.

3 . The method of claim 1 , wherein the EEPP is a general performance cycle model of the turbofan aircraft engine in a specific configuration on a model of the aircraft.

4 . The method of claim 2 , wherein the corresponding ΔNE values from the first tables are ΔNE values interpolated from ambient conditions and the engine observed parameters of N2, ITT, and PB.

5 . The method of claim 1 , wherein the aircraft computer compares the derived fan work scaling to a predetermined range, and

recommends to redirect the aircraft headwind and repeat the outdoor power assurance check test if the derived fan work scaling is out of the predetermined range.

6 . The method of claim 1 , further comprising the aircraft computer triggering a maintenance action upon a calculated HPC deterioration or a calculated HPT deterioration value exceeding a threshold value.

7 . A system for crosswind compensation of an outdoor power assurance check test of a turbofan aircraft engine of an aircraft, comprising:

a first non-transitory storage medium having stored thereon first tables representing average new engine (ΔNE) installed performance determined by running an estimated engine performance program (EEPP) to get expected values of a rotational speed of a high-speed spool (N2), an indicated turbine temperature (ITT), and combustor pressure (PB) with no deterioration and no crosswind effects;

a second non-transitory storage medium having stored thereon second tables of sensitivities of N2, ITT, and PB to high-pressure compressor (HPC) deterioration, high-pressure turbine (HPT) deterioration, and fan work scaler determined by running the EEPP;

an aircraft computer;

aircraft sensors configured to provide engine parameters of N2, ITT, and PB at an N1R1A to the aircraft computer;

stored power assurance check test instructions configured to execute on the aircraft computer to:

activate a brake of the aircraft;

close the turbofan aircraft engine bleed system, hydraulic, and electric loads;

bring the turbofan aircraft engine to Take-off power;

record ambient and the engine parameters of N2, ITT, and PB at the N1R1A once the turbofan aircraft engine is stabilized;

bring the turbofan aircraft engine back to idle;

calculate a difference between the engine observed engine parameters of N2, ITT, and PB at the N1R1A and corresponding ΔNE values of from the first tables as first deltas ΔN2, ΔITT, and ΔPB;

using the sensitivities from the second tables and the first deltas ΔN2, ΔITT, and ΔPB, solve a 3×3 system of equations to get fan work scaling, an HPC efficiency debit, and an HPT efficiency debit;

calculate second deltas ΔN2, ΔITT, and ΔPB to ΔNE performance without inlet bulk swirl effect using the sensitivities from the second tables and a calculated engine HPC deterioration and HPT deterioration without fan work scaling; and

calculate engine field margins for N2 and ITT by subtracting the second deltas ΔN2 and ΔITT from ΔNE field margins as an output for the outdoor power assurance check test.

8 . The system of claim 7 , wherein the first tables include data determined by running the EEPP to a plurality of possible combinations of altitude, Mach number, temperature, humidity, and fan corrected speed N1R1A to get the expected values of N2, ITT, and PB.

9 . The system of claim 7 , wherein the EEPP is a general performance cycle model of the turbofan aircraft engine in a specific configuration on a model of the aircraft.

10 . The system of claim 7 , wherein the corresponding ΔNE values from the first tables are ΔNE values interpolated from ambient conditions and the engine observed parameters of N2, ITT, and PB.

11 . The system of claim 7 , further comprising stored instructions configured to cause the aircraft computer to trigger a maintenance action upon a calculated HPC deterioration or a calculated HPT deterioration value exceeding a threshold value.

12 . The system of claim 7 , further comprising stored instructions configured to cause the aircraft computer to:

compare the derived fan work scaling to a predetermined range, and

recommend to redirect the aircraft headwind and repeat the outdoor power assurance check test if the derived fan work scaling is out of the predetermined range.

13 . An aircraft computer for performing an outdoor power assurance check test of a turbofan aircraft engine of an aircraft with crosswind compensation, comprising:

at least one processor;

at least one non-transitory storage medium having stored thereon:

first tables representing average new engine (ΔNE) installed performance determined by running an estimated engine performance program (EEPP) to get expected values of a rotational speed of a high-speed spool (N2), an indicated turbine temperature (ITT), and combustor pressure (PB) with no deterioration and no crosswind effects;

second tables of sensitivities of N2, ITT, and PB to high-pressure compressor (HPC) deterioration, high-pressure turbine (HPT) deterioration, and fan work scaling determined by running the EEPP; and

power assurance check test instructions configured to execute on the at least one processor to:

activate a brake of the aircraft;

close the turbofan aircraft engine bleed system, hydraulic, and electric loads;

bring the turbofan aircraft engine to Take-off power;

record ambient and engine observed parameters of N2, ITT, and PB at an N1R1A once the turbofan aircraft engine is stabilized;

bring the turbofan aircraft engine back to idle;

calculate a difference between the engine observed parameters of N2, ITT, and PB at the N1R1A and corresponding ΔNE values of from the first tables as first deltas ΔN2, ΔITT, and ΔPB;

using the sensitivities from the second tables and the first deltas ΔN2, ΔITT, and ΔPB, solve a 3×3 system of equations to get fan work scaling, an HPC efficiency debit, and an HPT efficiency debit;

calculate second deltas ΔN2, ΔITT, and ΔPB to ΔNE performance without inlet bulk swirl effect using the sensitivities from the second tables and a calculated engine HPC deterioration and HPT deterioration without fan work scaling; and

calculate engine field margins for N2 and ITT by subtracting the second deltas ΔN2 and ΔITT from ΔNE field margins as an output for the outdoor power assurance check test.

14 . The aircraft computer of claim 13 , wherein the EEPP is a general performance cycle model of the turbofan aircraft engine in a specific configuration on a model of the aircraft, and

wherein the first tables include data determined by running the EEPP to a plurality of possible combinations of altitude, Mach number, temperature, humidity, and fan corrected speed N1R1A to get the expected values of N2, ITT, and PB.

15 . The aircraft computer of claim 13 , wherein the corresponding ΔNE values from the first tables are ΔNE values interpolated from ambient conditions and the engine observed parameters of N2, ITT, and PB.

16 . The aircraft computer of claim 13 , further comprising stored instructions configured to cause the at least one processor to trigger a maintenance action upon a calculated HPC deterioration or a calculated HPT deterioration value exceeding a threshold value.

17 . The aircraft computer of claim 13 , further comprising stored instructions configured to cause the aircraft computer to:

compare the derived fan work scaling to a predetermined range, and

recommend to redirect the aircraft headwind and repeat the outdoor power assurance check test if the derived fan work scaling is out of the predetermined range.