This table contains information about the most common causes for a rocket to fail.
The intent is that, with proper care and prevention, these failure modes may be avoided. (Source From NASA Houston Rocket Club NAR Section 365)
| TASK/STEP | HAZARD | CAUSE | PREVENTATIVE MEASURE |
| Any | 1. Non-Hazardous Anomaly | Premature parachute ejection | All flights in this category result in safe landing under parachute. - |
| Flight preparations | 2. Premature motor ignition | Connecting igniter to live ignition system | - Using systems with a switch that returns to “off” when released per NAR safety code. Ensure continuity checker is igniter/electric match/flash bulb safe. |
| 3. Premature ejection charge ignition | Electronic Altimeter failure / capacitor discharge | -use switch or shunt on charge circuits until placed on pad | |
| Rocket boost | 4. Erratic boost | a. Rocket unstable | - Check the stability of the rocket with the selected motor per NAR safety code if not a proven design/motor combination -Use computer CG/CP program, CP should be 1.0 body diameter aft of CG |
| b. Unstable launch pad | - insure launch pad is sufficiently strong to withstand wind and launch forces. - use rail system for HPR launches | ||
| c. Too much wind | - Launch only in winds of less than 20 mph as required by NAR safety code - In windy conditions low thrust launches should be avoided. | ||
| d. Insufficient thrust | - Follow anufacturer¹s recommended maximum lift-off weight per NAR safety code - Use computer simulation program to determine thrust required | ||
| 5. Airframe failure | a. Improper construction | - Follow manufacturer assembly instructions. - On original designs use standard construction methods. - Check for secure fins, launch lugs, and proper nose cone fit. - Check secure motor mount assembly. | |
| b. Fin flutter | - Be sure to align grain with leading edge of fin. (standard construction method) - Avoid high aspect ratio fins | ||
| c. Improper Motor Selection | - Use care in selecting motor for flight. Follow manufacturer recommendations. - Follow manufacturer recommendations for max lift off weight per safety code. - Attempt high-G launches only rockets having appropriate construction. | ||
| 6. Catastrophic motor failure | a.Temperature cycling of black powder motors | - Store motors at a consistent temperature | |
| b. Improper construction | - Check all parts have been used (O-rings, ejection charge, spacers, etc.) - Check closures are tight, threads are not stripped. | ||
| Rocket recovery | 7. Failure to eject recovery system | a. Motor ejects from rocket | - Use motor retainer clips or sufficient tape to provide positive friction fit of motor - Be sure that recovery system not packed too tightly - Use heat resistant adhesives in motor retention system |
| b. Improper assembly of reloadable motors | - Build motor correctly following manufacturer directions - Avoid grease on delay element - Avoid crimping or damaging o-rings -Verify ejection port is clean and clear - Insure ejection charges are loaded | ||
| c. Electronics failure | - Verify system integrity before first flight or after major changes - Use motor ejection for redundancy | ||
| d. Failure of electronic recovery system to fire ejection charge | - Verify charge integrity with multi-tester or self-testing recovery system - Check mach lock-out settings on altimeter - Insure all hardware and electrical leads are installed properly and secured against flight loads. | ||
| e. Construction/ Preparation | - Too much wadding/packed too tightly - parachute packed too tightly - obstructions within body tube | ||
| TASK/STEP | HAZARD | CAUSE | PREVENTATIVE MEASURE |
| 8. Failure of chute to open | a. Recovery device stuck in rocket body | 1- Too much wadding 2- Recovery device too large or not packed properly 3- Insufficient ejection charge for size of body tube – see chart | |
| b. Parachute burned by ejection gasses | - Use flame-resistant recovery wadding or other protection system | ||
| c. Parachute shroud lines fouled | - Fold parachute carefully as described by manufacturer | ||
| 9. Strip of recovery system at deployment | a. Deployment occurred too early or too late | - Follow anufacturer¹s recommended maximum lift-off weight and/or computer simulation data. - Use electronic apogee detecting deployment system. - Use rocket flight simulation program to simulate flight determine best delay time. - Select shorter delays when winds are higher. The rocket will weather vane into the wind and shorter delays are required for proper recovery system activation. | |
| b. Improper construction | - Use proper hardware | ||
| 10. Separation of recovery or other system. | a. Recovery system improperly secured during preflight prep. | - For initial flight, or subsequent flights after repair, double check that the recovery system is properly attached to the rocket/payload section/nose cone. Inspect quick links, eyebolts, or other hardware to ensure that links are closed/locked and that other hardware is intact and secured. - Insure eye bolt connector will not un-screw during descent | |
| b. Failure due to wear and tear of flight operations | - Periodically inspect all components of the recovery system. Replace/repair burned or worn shock cords. Replace/repair parachutes with worn or frayed shroud lines. | ||
| 11. Rocket drifts into buildings / houses / trees | a. Parachute too large | Refer to parachute sizing guide and drift charts on back of checklist | |
| b. Too windy | Insure winds are within limits. Consider winds aloft information | ||
| c. Main parachute deploys early | -Use shear pins to secure main parachute compartment. -Use extra long shock cord and “metered deployment” of cord in drogue section. -Use proper amount of black powder in drogue ejection charge | ||
| 12. Rocket impacts prep area causing personal injury | Spectators not paying attention to rocket flight | - Use electronic PA system for all high power launches. - Launch Control Officer responsible for calling “Heads Up” -LCO give periodic detailed briefing to spectators on the meaning of ‘heads up’ and the corrective action to be taken -If possible, angle all flights away from spectators | |
| 13. Rocket impacts Buildings/houses in ballistic flight | Multiple failures | -Follow wind/altitude restrictions - see “failure to eject recovery system” |
NOTE: Preventative measure is not all inclusive and additional precautions may be required in order to maximize safe flying condition.