EMM 4103 Project
JT9D COMPONENT FAILURE ANALYSIS
The JT9D engine inventory reviewed in the presented study was installed on three different airframes, which included DC-10, B-747 and B-787. The review of the JT9D engine and these three airframes involved fourteen carriers, operating on a monthly average of 883 JT9D engines during the period of observation. The actuarial trending of in-flight shutdowns and unscheduled engine removals resulted in seven air carriers being examined more closely for specific component failure incidents.
The JT9D inventory was introduced into operational service in the mid-1960’s and had a rated thrust of 45.600 pounds. Various thrust growth models of the -7 engine were developed to include the -7Fat 48.000 pounds of thrust, the -7Q at 53.000 pounds of thrust and the -7R4G2 with 54.750 pounds of thrust. The JT9D-7R4G engine is considered to be a significant growth model of the engine, not just in thrust produced but in reliability enhancements. The table with failures related to the general components of the JT9D engine are presented below:
JT9D ENGINE INVENTORY FAILURE INCIDENT ANALYSIS
FOR SELECTED CARRIERS
COMPONENTS JT9D TOTAL* JT9D-7R4G
BEARINGS 35 2
AIRFOILS 80 1
CASES 13 0
FUEL / OIL SYSTEMS 84 5
CONTROLS & ACCESSORIES 366 7
OTHER 254 3
TOTAL 832 18
• Total lncludesJT9D-7R4G information
Review of the engine bearing failure incidents showed the #3 bearing to exhibit the highest number of failures with fifteen incidents reported. The failure modes documented involved leaking breather seals, carbon plugged scavenge tubes and cracked bearing compartments. For the six reported #4 bearing failure incidents, failed oil pressure lines, packings and the housing were the most common reported incidents.
Of the airfoil failure incidents reported, the eighth stage compressor blades and first stage turbine blades were the most prevalent. Ten eighth stage compressor blade failures were reported, with some failures in the root area of the blades. The thirty-seven first stage turbine blades reported generally failed one inch above the platform, although some failed in the root area. The turbine blade failures were due to material stress not foreign object damage (FOO).
The review of the failure data of the JT9D engine inventory showed controls and accessories to be a dominant failure trend. Of the 832 reported incidents for the five-year component trending period, 366 of all reported failures Involved controls and accessories. The following Table exhibits the type of component failures reported. Of the controls and accessories reviewed, the following five accessories exhibited the strongest trends: fuel control, fuel pump, engine vane controller (EVC), TT2 sensor and pressure ratio bleed control (PRBC). The fuel control and fuel pump each had numerous individual failure incidents as well as 25 reported incidents of removal of both items. Dual removals indicate the diagnostic trouble shooting information and practices were not sufficiently efficient to isolate fuel management problems to one particular item. In addition, dual removals of fuel controls and fuel pumps generate at least one good Item to depot repair, where a RETEST OK event occurs. This necessarily increases the workload and costs to the accessory backshop repair area.
Table of JT9D Engine Component Failures Incidents for Selected Carriers
Total incidents: 35
Bearing No. 1
Bearing No. 2
Bearing No. 3
Bearing No. 4
Total incidents 80
5th Stage compressor blades
7th Stage compressor blades
8th Stage compressor blades
13th Stage compressor blades
15th Stage compressor blades
1st Stage HPT blades
2nd Stage HPT blades
1st Stage HPT vanes
2nd Stage HPT vanes
Total incidents: 13
Fuel / Oil Systems
Total incidents: 84
Oil cap missing
Oil breather tube packing
Control and Accessories
Total incidents: 366
Fuel control/fuel pump
Fuel Pump Sheared shaft
Engine vane controller
Engine Electronic control
Thrust control computer
Pressure Ratio Bleed control
Bleed converter valve
8th Stage Bleed valve
15th Stage Bleed valve
HP Butterfly valve
TCC control valve
N2 Tech generator
Constant Speed Drive
Angle Gearbox Coverplate Stud
Total Incidents: 254
The EVC removals recorded 82 failure incidents over the observation period which represented 22 percent of all controls and accessories incidents. The following table reviews the impact upon aircraft operation resulting from EVC failures. The most frequent impact was to create engine compressor stalls with resultant shutdowns or flameouts, occurring during in cruise operation and turbulent weather conditions. Engine flameouts also occurred when initiating a descent flight profile.
JT9D Engine Vane Controller failure incidents for selected carriers
Engine Operational Characteristic
Stall/ Shut-down/ Flameout
Smoke Cabin Fume
RPM Spool-down/ Surge
Oil out bleeds/ High consumption
Due to the high failure rate of the Hamilton Standard EEC-103 engine electronic control unit for sufficient engine vane, bleed and fuel control of the JT9D-7R4 engines noted above, the quality engineer wants to further analyze the contribution in failures of circuit boards installed in the engine control units.
Variation in any process is the enemy of quality. So, he/she measures the response times in micro-seconds of circuit boards, taken as samples from production. The corresponding response times are presented in the following table:
Response time of 1st Unit (microseconds)
Response time of 2nd Unit (microseconds)
Response time of 3rd Unit (microseconds)
You as a member of the quality control department, you are asked to write a report that on the findings.
Plot the frequencies of failures of the JT9D engine general components and the frequencies of failures of engine subcomponents in cascading Pareto Charts to perform a Pareto analysis, identifying according to the 80/20 rule the most critical engine components as well as the most critical aircraft operation phases for failures of the engine vane controller.
Compute the values of mean and standard deviation of the above recorded sample date. Also, compute the values of and . How many parts of every 100 (percentage) produced items would you expect to scrap for acceptance rates: respectively? Produce a histogram using the given data and show the above acceptance rates. What would you have to do to bring the scrap rate at the acceptance rate of down to the scrap rate of . Compared with the curve produced before, what would the new histogram have to look like?
Make recommendations and support your arguments with logical assumptions based on the frequencies of engine components failures.
This project has to completed, printed and handed in for marking prior to the class on April 11th 2017. It must reflect professional standards. Marks will be deducted per day for projects handed in after this date.
The entire group of members of whatever it is your counting. If you are talking about a production process, the population is all the items that you produce using that process.
A subset of the population: In most cases, you can’t test all the items you produce so you have to test a representative sample.
The arithmetic average of all the values that you measure for a given test: You calculate the mean by adding up all the individual measurements and dividing by the total number of measurements
From the largest to the smallest. For instance a population of between 20 and 100 would have a range of 80.
Is a measure of the range of a variation around the average of a group of measurements. It’s the average distance that each measurement is from the mean of all the measurements. The Greek letter sigma (σ) refers to the standard deviation of an entire population.
This exercise will explain the steps necessary to calculate the standard deviation:
1/ the following five measurements were obtained from a process:
6, 8, 7, 9, and 10
2/ Add all the measurements up and divide by the number of measurements
6+8+7+9+10 = 40 divided by 5 = 8. This is the Mean.
3/ Take the difference of each measurement from the mean
6-8 = -2
8-8 = 0
7-8 = -1
9-8 = 1
The differences are therefore: -2, 0, -1, 1, and 2
4/ Square each of the differences
-2^2 = 4
0^2 = 0
-1^2 = 1
1^2 = 1
2^2 = 4
If you square a negative number it becomes positive.
5/ Add each of the squared values together
4 + 0 + 1 + 1 + 4 = 10
6/ Take the total at step 5 (10 in this example) and divide by the number of samples minus 1 (subtract 1) ( this is the sample factor)
10 Divide by 4 = 2.5
7/ Take the square root of 2.5 = 1.58
This is the calculated Standard deviation. The standard deviation is a means to examine the results of a process.
68.27 % of the population should be within + 1 standard deviation
95.45 % of the population should be within + 2 standard deviation
99.73% of the population should be within + 3 standard deviation
From this process, it is now possible to make use of the obtained figures.
8/ Plot the figures on a graph with the average shown.
9/ calculate the + and – for one, two and three standard deviations. Use the figures as shown.
1σ = 1.58 + 8 = 9.58, 8-1.58=6.42
2σ = 3.16 + 8 = 11.16, 8-3.16 = 4.84
3σ = 4.74 + 8 = 12.74, 8- 4.74 = 3.26
In this instance, let us assume that the ideal is the same as the average 8
10/ Add the above lines for +1, 2 and 3 standard deviations to the graph
Using the sample data given and based on the sample size choose the number of intervals for the histogram:
Size of Sample <75, then number of intervals 5-7 Size of Sample 75-300, then number of intervals 6-10 Size of Sample >300, number of intervals 10-20.
Or use formula: number of intervals=square root of sample size.
Count number of data in each interval.
Plot frequencies (i.e. number of data for each interval) to obtain the histogram, label appropriately, show mean and one, two and three standard deviation levels.
Our Service Charter
Excellent Quality / 100% Plagiarism-FreeWe employ a number of measures to ensure top quality essays. The papers go through a system of quality control prior to delivery. We run plagiarism checks on each paper to ensure that they will be 100% plagiarism-free. So, only clean copies hit customers’ emails. We also never resell the papers completed by our writers. So, once it is checked using a plagiarism checker, the paper will be unique. Speaking of the academic writing standards, we will stick to the assignment brief given by the customer and assign the perfect writer. By saying “the perfect writer” we mean the one having an academic degree in the customer’s study field and positive feedback from other customers.
Free RevisionsWe keep the quality bar of all papers high. But in case you need some extra brilliance to the paper, here’s what to do. First of all, you can choose a top writer. It means that we will assign an expert with a degree in your subject. And secondly, you can rely on our editing services. Our editors will revise your papers, checking whether or not they comply with high standards of academic writing. In addition, editing entails adjusting content if it’s off the topic, adding more sources, refining the language style, and making sure the referencing style is followed.
Confidentiality / 100% No DisclosureWe make sure that clients’ personal data remains confidential and is not exploited for any purposes beyond those related to our services. We only ask you to provide us with the information that is required to produce the paper according to your writing needs. Please note that the payment info is protected as well. Feel free to refer to the support team for more information about our payment methods. The fact that you used our service is kept secret due to the advanced security standards. So, you can be sure that no one will find out that you got a paper from our writing service.
Money Back GuaranteeIf the writer doesn’t address all the questions on your assignment brief or the delivered paper appears to be off the topic, you can ask for a refund. Or, if it is applicable, you can opt in for free revision within 14-30 days, depending on your paper’s length. The revision or refund request should be sent within 14 days after delivery. The customer gets 100% money-back in case they haven't downloaded the paper. All approved refunds will be returned to the customer’s credit card or Bonus Balance in a form of store credit. Take a note that we will send an extra compensation if the customers goes with a store credit.
24/7 Customer SupportWe have a support team working 24/7 ready to give your issue concerning the order their immediate attention. If you have any questions about the ordering process, communication with the writer, payment options, feel free to join live chat. Be sure to get a fast response. They can also give you the exact price quote, taking into account the timing, desired academic level of the paper, and the number of pages.