Like most AOA members, I fly my Aerostar (N88CX) for transportation, both business and personal. Again like most of us, I also am responsible for maintaining my bird. This presents a challenge for me, because I do not have the training and background to make intelligent decisions about that maintenance.
We should all have trusted advisors to call and help us make those decisions and there are some great “gurus” out there. Additionally, most of us have local mechanics who do a great job performing much of the work. But we cannot expect them to know all the details about our airplane.
Not unlike healthcare decisions, the more informed we are, the better our decisions will be. To that end, I set about getting more informed about aircraft maintenance. My priorities were:
- Maximize aircraft reliability and safety.
- Exercise preventive maintenance but not just part swapping.
- Know how old and how many hours are on a part.
- Understand how the systems operate in detail.
- Be able to detect any trends.
N88CX has been in the family for a while. My father, Bud Champlin, bought it from Ted Smith in 1976. I earned my MEL in it. When Bud passed away in 2008, it was put up for sale. After a couple of years of sitting in Alabama, with Don Smith’s help, I was able to purchase it.
I had the time and desire to really get involved with the maintenance. Going through the log book, I thought “Hey, I can put this on a spreadsheet”. Anyone who knows me, knows of my penchant to put things on a spreadsheet.
Starting from the back of the log books, I typed in parts and dates. Looking it over, I added more details and created a way to immediately know if something needs attention. The result after many hours is a spreadsheet available at (right click and open in new window using Excel):
You can download the spreadsheet and modify it for your aircraft. If you are not Excel savvy, maybe your mechanic or someone you know is. You can use it on an iPad but some of the formatting and color coding may not work right.
Open the spreadsheet and look at the first tab “Major Components”. It seems complicated at first but not so much after you give it a chance. I put it together starting with the most recent entries in the log books and worked backwards. I also looked at old invoices, since I had them available. Now I just pull it up on my laptop or iPad to see when a part was replaced, how many hours are on it, who did the work, etc. I can even pull it up on my Android phone.
For me, it has become a valuable tool for planning. For example, I was having trouble getting full MAP at altitude on the left engine. We rebuilt the air box, replaced induction hoses, etc. to no avail. I looked at the spreadsheet and noticed that one of the turbos had over 1,000 hours on it. It wasn’t pumping oil and there were no noticeable cracks. We replaced it and I get full MAP at the flight levels.
As I look at the spreadsheet, I notice that the engine hoses have 939 and 1169 hours and are more than 10 years old. I am planning at the next annual to replace the right one and the left one the following year.
Here are some pointers about the spreadsheet:
- – There are tabs across the bottom for Major Components, AD’s, Service Bulletins, etc. I use the Major Components mostly. If you notice some of the other info not being up-to-date, please let me know.
- – I have not protected any cells so be careful what you change.
- – The blue cells are for you to change. You may also change the item description. Be careful about changing other cells as they may contain formulas.
- – At the top put in your current Model, N number, Serial #, date and hobbs time.
Then go through and make changes as appropriate. - – The Hours on (column M) and Time on (column N) columns are calculated so do not type over the formulas there.
- – The colored Status (column B) is determined by the difference between time or hours on the part and the stated Insp/Repl hours or months (columns K & L). It is green if the time is less than 90% of the Insp/Repl hours or time. Between 90% and 100% it is yellow. At 100% it turns red. For example, the Fuel Valve 1 Left has 1012 hours on it and is red. That is because I set 1000 hours as the time I wanted to use as an upper limit. That number is arbitrary. I now need to decide if I want to overhaul the valve or move the limit up.
- – If you change the hobbs at the top to 5000 hours you can see that several items turn yellow and red. (For experts only – the color is determined using rules. You can see those rules by going to Home tab –>; Conditional Formatting –>; Manage Rules.)
- – Some of the Insp/Repl times and/or months are determined by AD’s, the manufacturer, etc. such as windshield time. Others are for my personal use such as Hose Kit.
- – This currently set up for Part 91 only. If you are Part 135 many items would have to have additional replacements on them.
- – To add a new row, select the entire row by left clicking on the number in the very far left. Then right click to bring up options and select “Copy”. Select the row below where you want to add a row, right click and select “Insert Copied Cells.” At some point you may want to renumber Column A.
- – It was written using Excel 2016. I have not tested it on older versions.
- – Some of the features like the colored Status cell do not work in Mac or iPad format.
- – I am not an A&P or even a mechanic, so if something looks out of whack, please let me know.
- – You can use DocsToGo or a Dropbox account to make it available anywhere you go.
There you have it. If my battery seems to be getting weak I can look and see the make, model, serial number, who installed it, when it was installed and how many hours it has on it. Pretty cool huh? I try to keep all information on the spreadsheet so it is handy right down to bulb types, spark plug information and paint colors.
Use this as a start and modify it for your aircraft. There is no reason you couldn’t use it for a different make and model. Get a handle on your aircraft maintenance by being informed.
If you have a questions or problems, let me know.
– Joel
